Chapter 13- Introduction to Entomology and Integrated Pest Management

Authors

• Frank Hale, Retired Professor & Extension Specialist, University of Tennessee
• Bill Klingeman, Professor, University of Tennessee
• Amy Dismukes, Former Extension Agent, Tennessee State University

With content revised and edited from a previous handbook in chapters written by Frank Hale (Entomology), Harry Williams (Entomology), and Bill Klingeman (IPM)

Introduction

Previous chapters of this handbook focus on plants in the landscape and the soil they inhabit. However, any gardener knows that the diversity of living things extends far beyond the plant kingdom. Plant communities interact intimately with a wide range of insects. In fact, as an Extension Master Gardener volunteer, you will likely find that a large proportion of the questions you receive will deal with plant–insect interactions.
The first two sections of this chapter describe insects and other arthropods in terms of their anatomy and the roles they play in the ecosystem. The focus then turns to the types of plant injuries that insects may cause and ways of determining whether the extent of injury is sufficient to warrant applying management measures.
The overall process of integrated pest management (IPM) begins with gaining an understanding of insects and their impact on plants with due regard for the natural environment. IPM was briefly introduced in Chapter 4 as an important practice in sustainable management. This chapter provides greater detail about applying IPM methods in lawns, gardens, and landscapes.
With knowledge of IPM principles and practices, Master Gardeners can help others make informed decisions that solve their immediate, specific problems while helping to sustain the long-term functioning of gardens and landscapes.
As an aid in applying IPM principles and practices, the final section of this chapter provides descriptions and images of many of the most common garden and lawn insects, including not only pests but also beneficial organisms.

Entomology Basics

Arthropods and Their Anatomy

Arthropods comprise the most diverse and populous phylum in the animal kingdom. In addition to all insects, it includes organisms such as sowbugs (which are not actually insects), lobsters, crayfish, crabs, shrimp, barnacles, millipedes, centipedes, sea spiders, scorpions, spiders, and many others.
Arthropods have a number of characteristics in common:

• a segmented body
• paired segmented appendages
• bilateral symmetry
• an outer covering (exoskeleton) that is shed and renewed to allow the animal to grow
• an open circulatory system
• an anterior brain
• respiration by means of tracheae, spiracles, or gills.

The illustrations below provide an example of how one arthropod —the grasshopper, which is an insect —fits into the scientific classification system, as compared with the human. Both are in the Animalia kingdom, but humans are in the phylum Chordata and class Mammalia, whereas the grasshopper is in the phylum Arthropoda and the class Insecta.
The most common classes of arthropods include Crustacea, Diploda, Chilopoda, Arachnida, and Insecta. The first four are discussed here briefly, while the rest of the chapter focuses mainly on Insecta. Sowbugs are in the class Crustacea. Each of the seven thoracic segments bears a pair of leglike appendages. When disturbed, they can roll up into a ball. They can be pests of cultivated plants in some parts of the world but are seldom even considered a minor pest in Tennessee, preferring to feed on organic debris.
Millipedes are in the class Diploda and are usually found in damp places where they feed on decaying plant matter. They are cylindrical in shape and have many body segments. Most of the body segments bear two pair of legs for a total of 30 or more pairs.
Centipedes are in the class Chilopoda. They are flatter than millipedes and elongate with 15 or more pairs of legs. There is a single pair of legs on each segment. They are fast moving and have a pair of clawlike appendages that function as poison jaws to subdue their prey.
Scorpions, spiders, mites, and ticks are in the class Arachnida. Arachnids have eight legs and some, such as scorpions, have enlarged appendagelike mouthparts with which they can grasp their prey. Spiders are important predators in the landscape and elsewhere. While most species of spiders are considered quite beneficial, brown recluse and black widow spiders have particularly toxic venom. Mites have sucking mouthparts and are pests of plants and animals. They are sometimes predators of small insects. Ticks are animal parasites.

Insects: Their Anatomy and Growth

Insects are incredibly diverse and numerous. In fact, nearly 75 percent of all animals are insects. They can live in almost all types of climates and regions of the earth with the exception of some polar and extremely mountainous areas. This wide range of insects feed on a variety of food sources. Some insects are scavengers, feeding on dead plants and animals. Others feed on green plants, while still others feed on other animals. These final two categories are the ones most likely to interest gardeners because they include the majority of our pest and beneficial insects.
Insect anatomy is quite similar to that described previously for arthropods. Their segmented body is divided into the head, thorax, and the abdomen. (see Figure 1.) Some parts they have in common include their eyes (compound or ocelli single eyes), mouthparts, and antennae on the head; three pairs of legs and two pairs of wings on the thorax; and an abdomen that usually lacks appendages except for reproductive parts. (see Figure 2.)
Several characteristics enable insects to be successful in so many climates and situations. These include a durable, lightweight exoskeleton that supports the organism’s success and survival in many different environments, their small size (in most cases), a short interval between generations and hence a high rate of birth, efficient use of energy for flight, and the process of metamorphosis (discussed below) that provides advantages in feeding and reproduction.
Metamorphosis is a process by which an insect changes form between the egg, immature, and adult stages. That difference in form can be an asset, enabling immature insects in the larval stage to survive in an environment that is more conducive to their growth and development than the world they will inhabit as adults.
The young insect is covered with an essentially firm skin called the exoskeleton made of the carbohydrate chitin along with proteins, waxes, and minerals. As the insect feeds, it grows inside the skin, but growth in volume is restricted by the original exoskeleton. A new elastic exoskeleton then forms under the old rigid exoskeleton. The old exoskeleton splits along the back and the insect crawls out of its old skin and expands to its new size.
The insect is most vulnerable to predation and pesticides immediately after shedding the old exoskeleton. After exposure to air for a short time, the new exoskeleton becomes hardened and the insect is ready to resume activity and growth.
The process of shedding the old skin is called molting. Molting occurs several times over varying periods of time until the insect reaches the final stage of maturity. With each molt, there is a change in form (besides the size change) that varies among the various insects. There are four types of metamorphosis, but this discussion will focus on two of the primary types.

Gradual (Simple) Metamorphosis

Gradual, or simple, metamorphosis consists of three developmental stages: egg, nymph (immature insect), and adult. In gradual metamorphosis, the nymphs resemble the adult insects. However, with each instar (stage of development), the legs and head become smaller in proportion to the rest of the body. This difference develops because the head and legs do not grow as fast as the rest of the body. In addition, in winged insects, the wings develop further with each molt. Molting is completed in winged insects after the fully developed, winged adult emerges.
The nymphs of insects that undergo gradual metamorphosis inhabit the same places and eat the same kind of food as the adults. Examples include plant bugs, grasshoppers, stink bugs, squash bugs, aphids, and leafhoppers.

Complete (Complex) Metamorphosis

In complete, or complex, metamorphosis, all four stages of development — egg, larva, pupa, and adult — will occur. All increases in size occur during each subsequent larval stage. At the end of the larval stage, the insect transforms into a pupa that does not feed or move about except to wiggle inside the pupal skin. It is sometimes called a resting stage, but inside the pupal skin drastic changes are taking place. More alteration of form occurs during the pupal stage than during any other period of the insect’s development. Once the pupa stage is complete, a fully formed adult emerges, complete with wings. No further molts occur after the adult emerges.
The larvae of these insects may live on different food, have different kinds of mouthparts, or exhibit other differences from the adults. The larval stage of some orders of insects are called maggots (for flies), grubs (for beetles), or caterpillars (for moths and butterflies). Examples of pests that undergo complete metamorphosis are Mexican bean beetles, cabbage loopers, hornworms, flies, June beetles, cutworms, armyworms, and butterflies.

Insects and People

Humans and insects have a long history of interaction that is both positive and negative. Many insects are parasites that feed on or transmit diseases to their human hosts, while others damage crops both during growth and after harvest. Insects can also diminish human quality of life through their effects on structures and residences. Even though insects can negatively affect humans in many ways, they also play a number of positive roles. Insects are factors in many environmental processes involved in soil formation and organic matter breakdown. Insects serve as a key link in many food chains and provide a food source for many fish, birds, and mammals, and thus for humans. In some cultures, insects are also a direct food source.

Positive Roles of Insects for Plants and Gardens

Gardeners have often gone to great trouble and expense to destroy insects, only to learn that they were harmless or were actually protecting plants by eating destructive insects. The many benefits and values of insects must be studied carefully to understand all the relationships with nature and horticultural crops. Insects are beneficial to the plant landscape and garden in several ways:

• One of the most important roles of insects is pollinating flowers, thus enabling the reproduction of plants in addition to the production of many fruits, seeds, and vegetables. Many common fruits and vegetables are pollinated by insects, including apples, blueberries, squash, almonds, and others. Also, many ornamental plants, both in the greenhouse and outdoors, are pollinated by insects, including chrysanthemums, irises, orchids, and yuccas.
• Some insects feed on other insects, which can help control pest insects.
• Insects improve the physical condition of soil and promote its fertility by burrowing throughout the surface layer. Also, the dead bodies and droppings of insects serve as fertilizer.
• Insects perform a valuable service as scavengers by devouring dead plants and animals, burying carcasses, and burying dung.
• Insects attack various weeds in the same ways they injure desirable plants.

Insects as Plant Pests

Plant Injury Caused by Insects

Injury by Chewing Insects

Insects consume their food in a variety of ways. One method is by chewing on parts of a plant. Such insects are, not surprisingly, called chewing insects, and their impact can be seen simply by examining plant leaves. If many leaves appear to be chewed, chewing insects may be causing the problem. Cabbage loopers, armyworms, grasshoppers, Japanese beetles, sawflies, Colorado potato beetles, and fall webworms are common examples of insects that cause injury by chewing.

Injury by Piercing-Sucking Insects

Insects also take in food by piercing a plant’s epidermis and sucking sap from the cells or by injecting digestive juices (saliva) and eating dissolved plant tissue. Even though the insect feeds externally on the plant, only the internal liquid portion of the plant is consumed. These insects have a slender, sharp, pointed portion of the mouthparts that is thrust into the plant. The resulting injury appears very different from that caused by chewing insects.
The hole made from piercing-sucking insects cannot usually be seen with the unaided eye. However, this feeding may result in tiny spots of white, brown, or red on leaves, fruits, or twigs; curling leaves; deformed fruit; shedding of flower buds or fruit; or general wilting, browning, and dying of the entire leaf or plant. Aphids, scale insects, squash bugs, stink bugs, leafhoppers, and plant bugs are common examples of piercing-sucking insects.

Injury by Internal Feeders

Many insects feed within plant tissues during part or all of their life stages. They gain entrance to plants either in the egg stage when the female deposits eggs into the plant tissue or after they hatch from the eggs by eating their way into the plant. In either case, the entry hole is generally quite small. A large hole in a fruit, seed, nut, twig, or trunk generally indicates where the insect has come out, not where it entered.
The names of the chief groups of internal feeders reflect their method of feeding: borers in wood or pith; worms (larvae) or weevils in fruits, nuts, or seeds; and leaf miners in leaf tissue. Borers, worms, and weevils are some of the most damaging insect pests in the world. It is one or more of the immature life stages that usually feed inside the plants before the adults emerge. Control measures are most effective when aimed at adults or the immature stages before they enter the plant.

Injury by Subterranean Insects

Subterranean insects attack plants below the surface of the soil. They may chew or bore into roots, suck sap, or cause the formation of galls. The attacks differ from the above-ground forms only because of their position below the soil surface. Some subterranean insects such as termites spend much of their life cycle below ground or feeding on wood near or in contact with the soil. Winged adult reproductive stages emerge from the soil and disperse to form new colonies. These adults are often the first indication that a termite colony is nearby and potentially feeding on the structure in or near which they were found.
The woolly apple aphid, as both a nymph and an adult, sucks sap from the roots of apple trees, causing the development of tumors and subsequent decay of the tree’s roots.
Other subterranean insects have at least one life stage that is not subterranean. Examples include wireworms, root maggots, strawberry root weevils, the grape root borer, and corn rootworms. The larvae are root feeders, whereas the adults live above ground.

Injury by Laying Eggs

An estimated 95 percent of insect injury to plants is caused by feeding in the various ways just described. In some cases, however, injury is caused by laying eggs in critical plant tissues.
Periodical cicadas with either a 13-year or 17-year life cycle oviposit two rows of eggs in 1-year-old growth of fruit and forest trees. (see adjacent photo.) This oviposition can split the twig so severely that the entire twig often dies and the leaves turn brown. This is called flagging, and many of these flagged branches can break off and litter the ground. Flagging is particularly damaging to the limb structure of young ornamental nursery and fruit trees. Once the eggs hatch, the nymphs drop from the twigs, dig into the soil, and start feeding on the tree roots. While all but a month or so of the periodical cicada’s life cycle is spent as a nymph feeding on roots, this does not appear to significantly injure the tree.
Gall insects and mites cause plants to produce a structure of deformed tissue called a gall in which the immature insects develop to adulthood. The growth of the gall is initiated by the adult laying eggs inside plant tissue, and the continued development results from secretions of the developing larva. Inside the gall, the insect finds shelter and food needed for its complete development. The general size and shape of a gall is characteristic of a specific type of gall insect or mite on that particular plant and can often be used for identification purposes.

Injury by Using Plants for Nest Materials

Besides laying eggs in plants, insects sometimes remove parts of plants for the construction of nests or for provisioning nests. However, these effects are rarely threatening to overall plant health. Leaf-cutter bees nip out rather neat, circular pieces of rose and other foliage that are carried away and fashioned together to form cylindrical cells in which the immature bees develop.

Injury by Spreading Plant Pathogens

In 1892, it was discovered that fire blight of fruit trees was spread by the honeybee. At present, there is evidence that more than 200 plant diseases are disseminated by insects. Some common diseases and their insect vectors are listed in Table 1. The majority of them, about 150, belong to the group known as viruses, 25 or more are caused by parasitic fungi, 15 or more are bacterial diseases, and a few are caused by protozoa.
Insects may spread plant pathogens in these ways:

• feeding, laying eggs, or boring into plants, creating an entrance point for a pathogen that is not actually transported by the insect
• carrying and disseminating causative agents of the pathogen on or in their bodies from one plant to a susceptible surface of another plant
• carrying pathogens on the outside or inside of their bodies and injecting plants hypodermically as they feed
• serving as an essential host for some part of the pathogen’s life cycle, meaning that the pathogen could not complete its life cycle without the insect host.

Dealing with Insect Pests and Mites in the Landscape and Garden

Even though we know that insects can provide a number of benefits, often the focus of gardeners is on the control of pest insects in gardens and landscapes. In addition to the control measures that humans employ, a number of natural factors are at work. Beneficial arthropods, such as green lacewings, lady beetles, parasitoid wasps, and spiders help maintain many populations of pests at low to moderate levels.
In addition, naturally occurring disease organisms such as fungi, bacteria, and viruses help regulate pests. However, many pests, such as the Japanese beetle, euonymus scale, gypsy moth, black vine weevil, and the granulate ambrosia beetle have been introduced to the United States (including Tennessee) from other parts of the world. These pests were introduced without the complex of natural enemies that help moderate their populations in their place of origin.
The challenge for professionals engaged in plant production and management as well as home gardeners and growers is to understand and manage our gardens and landscapes in a way that minimizes the impact of native and introduced pest insects while maximizing the survival and effect of beneficial insects and other organisms that help moderate pest populations. This task is one important component of the comprehensive approach called integrated pest management, or IPM.

Steps to Sound Application of Integrated Pest Management

1. Scout for pests and diseases; closely observe plant stems, leaves, bark, and roots for signs and symptoms of arthropod activity and plant diseases.
2. Identify the pest or disease; use the library, Internet, and illustrated guides, and contact Extension Master Gardener peers or your local Extension agent to confirm that the pest or disease is harmful to your plants, then determine if the pest is still present before applying control strategies.
3. Decide which management strategies will be most effective.
4. Implement your management plan; take action in time to achieve control and target the most susceptible life stages of the pest or disease.
5. Record your management action. What did you do? When did you do it? If you used a pesticide, which chemical and mode of action did you use and at what rate?
6. Observe the result of your management action; which factors may have played a role in the success or failure of your effort? What will you do differently, or will you do the same thing again, next time you encounter the pest?

Introduction to Integrated Pest Management

Some important concepts in integrated pest management (IPM) are:

• focusing on understanding pests and managing their total environments (ecosystems) in ways that will limit their damage
• monitoring pest numbers and damage and correctly identifying pests to help determine whether management is needed and, if so, what methods should be used
• combining a number of management methods to increase effectiveness and limit the potential risks to humans, animals, environmental quality, and beneficial insects.

Keep in mind that a “pest” can be an insect, pathogen, weed, or other factor that limits plant production, affects human health, diminishes environmental quality, or constitutes a nuisance. IPM concepts, then, can apply to a range of lawn and landscape issues. They are introduced here because IPM practices are most commonly used in dealing with insects and mites in the landscape and garden. However, control of weeds and diseases often rely on these principles as well. (see Chapters 14 and 15.)

Scouting

Inspecting Planting Locations for Insect Pests

When preparing to plant, inspect the soil of landscape beds and garden plots for pests. Detection of pests prior to planting alerts growers to apply soil insecticides before, or at, planting time.

Importance of Early Pest Detection

Once the plants are in the ground, the upper surface and the underside of the leaves, stems, blossoms, and fruits should be inspected for pests. If a pest is seen, it can be dislodged by shaking the foliage over white paper or cloth. It is important that plants be inspected at regular intervals throughout the growing season to minimize pest problems. Be aware that whitefly, aphid, and spider mite populations develop rapidly on the underside of leaves, and corn earworms infest ears of corn and the fruit of tomato plants. Early detection allows for timely control measures to limit pest damage.
It is important to know when to start looking for a particular pest. Many pests of ornamentals can first be detected as they become active in the early spring after overwintering. Detecting pest populations early with scheduled plant inspections and spot treatments is important if damage is to be prevented. An example of insect pests that must be caught early are most of the borers. Control measures are needed when the adults are active and laying eggs. Once signs of feeding are observed, the larvae are already actively feeding within the plant and the damage is done. Unfortunately, most pest problems are either not treated or are treated after significant plant damage has occurred.
In this chapter, some of the most common garden insect and mite pests are described. The emphasis is on how to detect and control these pests early. Some pests, such as the boxwood leafminer, eastern tent caterpillar, or bagworm, have only one generation per year. If the pest is controlled early, damage can be prevented for the rest of the year.
Control may be as easy as pulling the webbing that contains eastern tent caterpillars out of the tree and stepping on it. Other pests, such as spider mites, euonymus scale, or fall webworm have more than one generation per year, affording several opportunities to apply control measures.

Tools for Scouting

The proper tools are needed to successfully scout the landscape or garden. Tools for the IPM scout are inexpensive and easy to find. A complete kit, as described on page 13-16, can be assembled for less than $50.
One of the first items in the toolbox should be a small 10- to 16-power hand magnifier with a lens not less than ¾ inch (20 mm) across. The lens should be large enough that it is comfortable to use for extended periods. It is also important to have a pocketknife and small, zipper-lock plastic bags for collecting and preserving root or leaf tissues until they can be more thoroughly examined. A hand trowel is useful for observing the roots of plants or searching for soil-inhabiting pests.
In addition, landscape hedgerows, large shrubs, and patches of ground cover can be sampled quickly using a sturdy canvas sweep net. A square “beat” cloth or a light-colored pan can be used to catch arthropods shaken from plant branches and foliage. Alternatively, a clipboard or field notebook with a pale surface can be used as a backdrop to count mites or thrips shaken from plant foliage. A light-colored surface is important to allow contrast with the darker colors and shadows of small and slow-moving pests. Also, where scales are a concern, a piece of double-sided sticky tape can be used to monitor crawler emergence.
Finally, a small aspirator can be a great asset in pest scouting. An aspirator is a miniature vacuum device that enables small arthropods to be drawn into a collection vial. With an aspirator, the gardener can suck a small volume of air into a screened intake tube. The opening of a second flexible tube is then held close to the insect and the vacuum pulls the insect into the vial. Once the specimen is collected, a small volume of 70 percent isopropyl (rubbing) alcohol is added to the collection vial to preserve the specimen for subsequent identification. Use permanent ink to label each vial with the date, host plant, and collector.

Scouting Tools

• 10x to 16x magnifying hand lens for observing small mites, scale crawlers, and signs of natural enemies
• Clipboard and notepad for mapping infested areas and recording your actions and their results
• Sheets of white paper, a white pan, or a beat cloth for catching slow-moving pests (such as aphids, mites, and scale crawlers) that are easy to see on the light-colored background
• An aspirator for sucking smaller, flighty insects into a vial where they can be more easily observed
• A pocketknife for easily collecting root, leaf, or other plant tissue samples
• Zipper-lock bags and plastic vials for preserving pests or storing samples until they can be properly identified; Medicine bottles or film canisters can be also be used
• A hand trowel for observing the roots of plants or searching for soil-inhabiting pests and root diseases
• Double-sided sticky tape for monitoring emergence of scale crawlers on small twigs and branches
• A sturdy, canvas sweep net for sampling larger areas of turf or spaces within a hedgerow.

Scouting and Monitoring Techniques

Scouting: Where and How Often?

Gardeners spend a lot time in their gardens and landscapes. During that time, it is important to observe the beneficial and pest arthropods as well as disease symptoms and signs that can indicate the beginning of a potential problem. Regular and organized scouting is the key to successful landscape IPM. Scouting helps gardeners and landscape managers locate and identify pest populations before economic and aesthetic losses occur.
To get started, divide the landscape or garden into logical sections to scout and observe. Sections may represent an individual garden, a landscape bed, or different sections of a yard and can be divided by plant type, use pattern, or environmental exposure.

Scouting: Use of Plant–Pest Relationships

Gardeners do not need to inspect every plant in the landscape, or within a group, to be confident that pests and diseases are not at economically or aesthetically damaging levels. A simple method can help lower the burden of scouting. It involves being aware of plants in the landscape or garden that are commonly problematic or prone to certain issues. These plants are sometimes called ‘key plants’, but the main idea is for gardeners to become aware of common plant–pest relationships. Because many plants have well-established relationships with certain pests or diseases, they can be used as an early warning system. For example, eastern tent caterpillars, Japanese beetles, and fire blight disease threaten many crabapple cultivars and species. Azalea lace bugs are a common problem on evergreen azaleas, particularly in sunny, exposed landscape beds. Cabbage moth caterpillars are regular pests of broccoli and other cruciferous vegetables and greens.
Another good strategy for an IPM program is to use susceptible plants as “sentinels” for early activity of target pests. Garden beans (Phaseolus sp.) and roses (Rosa sp.) can be used to monitor spider mite populations. Tomatoes and lantana can be indicators of whiteflies, and aphid outbreaks can be detected on chrysanthemums. In a small greenhouse, grow seedling rye (Secale sp.) or wheat (Triticum sp.) in small containers adjacent to ornamental plants to detect fungus gnat activity.
Gardeners should keep in mind that pest populations can build quickly to plant-threatening levels on untended sentinel and trap plants. Therefore, it is important to scout plants regularly and treat — or remove and destroy — affected plants once pests are discovered.
Most pest populations develop in patchy distributions, rather than distributed evenly in landscapes and gardens. Therefore, at regular intervals along a hedgerow a single plant should be inspected for signs and symptoms of the presence of pests or diseases. It is permissible to be selective about which plants to inspect. Yellow (chlorotic), wilted, and damaged foliage are often indicators of disease or arthropod pest activity.
The stems and trunks of shrubs and trees should be examined for sunken lesions, oozing sap, torn bark, and sawdust. Leaf margins should be observed for notches, holes, discoloration, or leaf spots. About 10 to 15 leaves should be randomly selected from different heights and sections of the plant. Areas along the main veins and the undersides of leaves should be inspected for spider mites, eggs, aphids, and cast skins of other pests. On larger shrubs and trees, examine three to five 4-inch-long (10-cm) terminal stem sections per plant. Dense shrub centers where populations of protected pests first develop should not be ignored.

Plant Inspection

Scouts do not need to inspect every plant in the landscape, or in a group, to be confident that pests and diseases are not at economically or aesthetically damaging levels. It is okay to be biased about selecting which plants to inspect.
If pests are encountered, a greater number of plant parts — or plants in a group of similar plants — should be inspected to get a better estimate of pest population size. It is a good idea to use a colored flag or ribbon to mark the outbreak location so it can be found again when making spot treatments.

In general, most landscape and garden beds should be scouted at weekly or biweekly intervals. Because seedlings are more susceptible than mature plants to root rots, cutworms, and rodents, they should be scouted more frequently. With practice, it will take less than five minutes to scan the upper and lower leaf surfaces of new and old foliage, flowers, leaf axils, bark on the main trunk and stems, and the roots of a plant showing evidence of pests or disease. A ½-acre landscape can be scouted in about 45 minutes.

Scouting in Turf

Scouting turf is no more difficult than scouting landscape plantings and garden beds. To scout turf, scan for patches of discolored turf, thinning grass, spongy areas, or notable disturbances from foraging birds and mammals. Next, look closer for skeletonized leaves, clipped blades, webbing, or signs of feeding, such as frass or excrement. Mobile insects in thatch and soil can be flushed from turf with a mild soap solution. Dissolve 2 to 4 tablespoons of liquid dishwashing detergent in about 2 gallons of water and pour the solution over the turf surface, covering about a 2-foot by 2-foot square area (4 square feet). After about 5 to 10 minutes, sod webworms, cutworms, armyworms, and billbugs will move into the open where they can be collected and counted.
A 1-gallon coffee can with the ends cut off also works well as a reservoir to float mobile arthropods from turf. Push the edge of the can into the turf about 1 inch deep. Keep the can full of water, replacing the volume absorbed by the soil, for about five minutes. Chinch bugs, beneficial ground beetles, and other arthropods will float to the surface where they can be counted.
When less mobile pests are feeding and active, grass sections become loosely rooted and can be easily pulled free. To examine for these pests, use a flat-bladed spade to dig up about 1 square foot of turf. Then the grass roots can be examined as well as about a 3-inch-deep soil zone for pests or damage caused by pests.
Sticky Traps and Pheromone Lures
Bands of sticky glue, such as Pestik and Tanglefoot adhesives, keep highly mobile pests off greenhouse benches and restrict pest movement on trees. Sticky traps are commercially available in various colors. Yellow is the best choice for overall pest detection and is effective in attracting whiteflies, aphids, thrips, fungus gnats, and leafminer flies. Blue traps attract thrips. Sticky cards are most effective for monitoring pest populations in greenhouse and interior gardens. In the landscape, sticky cards quickly become clogged with dirt and dust, and they indiscriminately trap pest and beneficial arthropods.
Pheromone lures are another effective tool for monitoring pest populations that are difficult to observe directly. Pheromones are organic molecules that arthropods use to signal other members of their species —for example, for purposes of reproduction. They can be used to attract certain species to a trapping device, allowing beneficial and nonthreatening insects to remain safe. Traps may also be used to count pests to determine if treatment is needed.
Clearwing moth borers are some of the most problematic pests in the landscape. The moths are strong fliers as adults. Larvae feed beneath the bark and in the stems of many different host plants. At best, these behaviors make direct field observations difficult. To find one another in nature, these moths rely on volatile pheromones produced within their bodies and emitted as a social cue.
Pheromone cues are most frequently used by insects to find reproductive mates. Chemists have synthesized many of these compounds into lures or baits that attract pests to traps. Because pheromones work across distances that can exceed one mile, traps are used to detect the emergence and activity of pests within a season. When male moths that orient to the airborne reproductive signals are trapped, we know that mating and egg laying will be occurring. Scouts can monitor these traps and make preventive trunk treatments to susceptible host plants when clearwing moths are active in the landscape.

Identification

It is essential to be able to identify the organisms causing plant injury before initiating management actions. Sometimes, pest and disease problems can be readily identified using pictures and descriptions in garden magazines, lawn and garden maintenance books, and on the Internet. In other cases, plant symptoms are less obvious. Samples of plants with their symptoms can be taken to a landscape professional or garden center, shared with an Extension Master Gardener peer, or sent to a county Extension agent or the state diagnostics laboratory for accurate identification.

Management Strategies

Once a pest problem has been identified, information about the size and location of pest populations, knowledge about the developmental pattern of the pest, and an understanding of pest behavior can be used to develop a management strategy to limit additional population growth and plant damage. Management recommendations can be based on prior experience with the pest and the extent of plant injury it is likely to cause. UT Extension also provides control recommendations through county Extension offices and online.
To control the pest problem, an informed gardener has several options, including cultural, physical, mechanical, biological, and chemical controls, or replacing the plants with cultivars that have less potential for severe insect damage. Or the grower may elect to do nothing if the damage is negligible and not worth the time, money, or impact of control. Natural enemies and plant vigor can outcompete many pest population cycles.

Cultural Control Practices

Sanitation

In gardens and landscapes, sanitation is consistently the most neglected proactive approach to limiting pest introduction and population outbreaks. Dead and dying plants should be removed and destroyed, and removing dead leaves, twigs and mummified fruit can reduce reinfestation of a range of pests. Compost piles should not include slow-dying, drought-stressed, and infested plants. These “Garden Typhoid Marys” accelerate pest development and attract pest opportunists. As the resources in the compost pile fade, these pests leave the pile and move into the garden and the landscape.
Too often, weeds are overlooked in IPM planning. Yet weeds provide food and hiding places for pest arthropods. They also support fungal, bacterial, and viral diseases that spread to garden and ornamental plants. On the other hand, weeds and grasses can supply pollen and nectar to arthropods’ natural enemies and provide refuges for both predatory as well as prey insects. However, many ornamental and marginally ornamental plants can perform the same function.

Plant and Cultivar Selection

Inappropriate plant selection and use can contribute to pest and disease problems, so always choose the “right plant” for the “right place” in the yard or garden. Pay attention to sun and shade exposures in the planting bed, and test the soil for pH and electrical conductivity. These conditions can affect nutrient availability and fertility. Finally, observe the planting location during and after moderate to heavy rainfall to become aware of potentially damaging drainage issues in the area. (see chapters 5, 7, and 8 for additional information.) When planting, handle the root ball with care, and irrigate promptly.
Not every cultivar within a species group, nor every species within a genus, is equally susceptible to arthropod pests. Pest and disease resistance in plants can be attributed to many factors. For example, resistance to Japanese beetles in certain apple and crabapple cultivars is attributed to the production of elevated levels of defense chemicals, which inhibit feeding activity. Physical differences, like dense trichomes (leaf hairs) on some buddleia and azaleas increase the pest resistance of those plants. Gardeners should take advantage of differences in plant susceptibility when designing IPM programs. Select pest- and disease-resistant plants for new gardens or to replace dead or dying susceptible specimens.
Be selective when purchasing plants and accept only pest- and disease-free plants. To be sure, courteously inspect leaves, stems, and roots closely before getting to the cash register. Inspect only the outside edges of root balls and then carefully replace the undisturbed roots and media back in their containers.

Mechanical and Physical Control Practices

Mechanical control strategies rely on labor, materials, or machinery to directly exclude pests and diseases from plants. Nets, hardware cloth screens, lightweight spun fabrics, and woven fabrics can be used to keep birds, rodents, and pests away from seedlings and sensitive crops. Copper strips can be used to exclude snails and slugs from garden beds. Burlap bands can be wrapped around tree trunks to shelter highly mobile tent caterpillars and gypsy moth larvae. These bands need to be visited regularly and the pest larvae, whenever found, submerged in soapy water.
By contrast, physical controls rely on environmental manipulations that alter temperature, light, or moisture in the growing environment. Pest populations are affected indirectly. Covering the soil with newspaper, plastic, and bark mulch and the use of soil solarization are common examples of physical controls that moderate soil temperature and moisture levels in the garden and landscape. Soil solarization, as described in Chapter 15 on weeds, is the process of killing pests by covering the soil with clear plastic mulch. This practice can increase soil temperatures to over 120°F, which can destroy certain weed tissues and plant pathogens in the upper 2 to 3 inches of soil. Solarization is a tool that can be used to prepare a site for annual or perennial crops but should never be used in conjunction with established perennial crops.
In addition, shade structures and vine-covered trellises can be used to limit midday sun exposure and alter the environment below. Proper irrigation timing, in the morning and early evening, and the irrigation method — for example, the use of drip irrigation and soaker hoses versus overhead irrigation— also influence leaf wetness, temperature, and humidity around the plants.

Biological Control Organisms

In a balanced ecological system, predators (that consume pests) and parasitoids (that weaken or kill pests by living on or in them) are efficient foragers for prey arthropods. These beneficial organisms can be conserved, encouraged, or released into landscape and garden beds. Architecturally complex landscapes, which gain diversity by mixing overstory trees and shrubs with perennials, groundcovers, and turf, contain more beneficial arthropods than simple plantings.
Supporting or using these predatory and parasitic organisms, though, requires knowledge and intentional management. Long-residual, systemic, and broad-spectrum insecticides and miticides may need to be avoided to conserve beneficial arthropods. Many arthropod natural enemies must be supplied with alternative pollen or nectar resources to survive when preferred food resources (the pest arthropods) decline in population. Garden and landscape borders can be designed to include several ornamental and marginally ornamental plants that are heavily visited by beneficial arthropods.
Pathogenic microorganisms (sometimes called biopesticides) are a third category of biological control organisms. Control involves encouraging or intentionally releasing microorganisms that cause disease in the pest population. Certain pathogenic bacteria, viruses, and fungi have been commercialized and can all be effective if used appropriately.

Chemical Control Philosophy and Practices

In an IPM program, chemical sprays are used only when necessary. Generally, the goal of IPM is not to eradicate a given pest but to reduce its population to a level that is acceptable in terms of the damage it causes. In fact, efforts to completely eliminate pest populations often result in pests becoming resistant to chemical controls.
In essence, if the only survivors of pesticide treatment are those that are unaffected by the chemical compounds, their offspring are more likely to be pesticide tolerant. However, this is not to say that chemical pesticides are unacceptable; they can be an integral part of a successful IPM program. Instead, to avoid overuse of chemical pesticides, they should be considered as only one option among several management alternatives.
Within an IPM framework, choose a pesticide after considering the expected ability to control the pest, the action of the pesticide on predatory and parasitic natural enemies and other nontarget organisms, and the mode of action of the pesticide’s active chemical ingredients. Pesticides should be applied during the most susceptible life stages of the target arthropod or disease. In short, correctly identifying the pest and understanding pest biology can optimize the effectiveness of a pesticide.
When a pesticide is selected as the best management option, emphasis is placed on making spot treatments to centralized pest populations rather than relying on calendar-based applications of sprays that cover the whole plant. Retreatment intervals should be timed to catch pests that emerge from pesticide-resistant life stages, such as eggs and pupae. Finally, the most efficient pesticide use is accomplished by continuing to monitor pest populations after management actions have been taken.

Pesticide Resistance and Chemical Mode of Action

In general, pests that develop rapidly and produce multiple generations within a season, such as spider mites, aphids, and thrips, are more likely to develop pesticide resistance. Methods of resistance could help pests detoxify chemical active ingredients or bypass their modes of action. Resistance can develop in a population of insects when susceptible insects are killed and those able to withstand the pesticides live to reproduce. This can select for genes within the population that can lead to more tolerance to the chemical in the future.
A pesticide’s mode of action describes which physiological processes or functional metabolic pathways of the insect are disrupted by the chemical’s activity — in other words, how a pesticide “stops the insect’s internal engine.” Mode of action is often related to the chemical class of the pesticide’s active ingredient. For example, Permethrin is a pyrethroid-class insecticide that disrupts the nervous system when arthropod pests contact or ingest the active ingredient.
Resistance is more likely to occur when the same pesticide — or different pesticides with the same mode of action— are applied repeatedly. Pesticide resistance can be limited by rotating chemicals with different modes of action after two or three consecutive treatments have been applied. As an alternative, groups of plants can be left untreated to allow susceptible pest populations to survive and interbreed with resistant populations.

Pest Resurgence

Pest resurgence can be confused with either treatment/product failure or with pesticide resistance. Pest resurgence occurs when a broad-spectrum insecticide is used to control a pest, but the pesticide also kills beneficial arthropods. When the natural enemies of the pest are eliminated, pests that survive treatment or that recolonize the crop develop without pressure from parasitoids and predators. As a result, subsequent pest populations may be larger than the initial pest population.
Phytotoxicity
Plants are susceptible to phytotoxicity, which is damage from pesticide volatilization, drift, or direct contact with the plants. Seedlings are more sensitive to pesticides than parent plants. Herbaceous plants are generally more susceptible than woody plants.
Exposure to direct sunlight and temperatures in excess of 86°F (30°C) can increase the severity of plants’ phytotoxic response. So, it is important to know when to apply pesticides to minimize the risk of plant tissue damage. Common symptoms of phytotoxicity include loss of protective waxes on leaves and needles (particularly among conifers treated with horticultural oils and insecticidal soaps), yellowing of leaves (chlorosis), premature fall coloration, spot necrosis on foliage and flowers, leaf curl, leaf drop, and plant death.

Oils and Soaps for Pest Management

Oils kill insects and mites by suffocation or membrane disruption. They are derived from petroleum or from hydrocarbon chains from plants. Summer or horticultural oils are highly refined and can be used on foliage at a 0.5 to 2.0 percent rate. Dormant oils are less refined and can be used on winter-dormant plants at a 2 to 4 percent rate. Citrus oil containing d-Limonene is usually combined with soaps. Horticultural oils can be phytotoxic to some plants and will remove the Colorado blue spruce’s blue blush. If experience in using horticultural oil on a particular cultivar is lacking, test spray a branch and evaluate for chemical burn or phytotoxicity before spraying the entire plant. Keep in mind that it could take several days for symptoms to appear and that the appearance of damage depends on the environment and overall health of the plant.
Insecticidal soaps consist of 6 to 10 carbon fatty-acid chains joined together by potassium or sodium ions. They can kill by disrupting the cell membranes of soft-bodied insects and mites such as aphids, soft scales, caterpillars, spider mites, beetle larvae, and mealybugs.
Both oils and soaps must contact the pest when applied to be effective, so good spray coverage is essential. Since there is very little residual insecticidal activity, oils and soaps should be safe for beneficial insects that immigrate to the plant after spray application, but they can kill soft-bodied beneficials (for example, immature lady beetles) if they are present during application. Some predaceous insects such as adult lady beetles have some tolerance to being sprayed with soaps and oils.

Assessing and Recording Management Actions

To be complete, an IPM program must include an evaluation of the management strategies that were chosen. After implementing a tactic, it is important to reevaluate and record the results. Did the action keep the plant looking healthy? Did eggs or pupae of the pest survive to recolonize the plants, or did they immigrate from untreated plants? Was the strategy worth the time and cost?
The final assessment should take into account important conditions that might have affected results. These conditions could include weather or the introduction of new plants, pests, or equipment. These factors may not seem important initially, but they often influence the success or failure of pest and disease management actions.

The Value of Good Record-Keeping

Keeping thorough and accurate IPM and scouting records is essential for the success of an IPM program. Perhaps the most important early objective of scouting records and maps is discovering the location of pest and disease “hot spots” in the garden or landscape. Hot spots are problem areas that more or less regularly contribute to seasonal population outbreaks.
Hot spots can be found in sunken zones or in shaded corners, in raised portions of the landscape, and adjacent to buildings or reflective windows. Once identified, hot spots can be monitored regularly to limit the severity of pest outbreaks. In our modern era, good records can also limit homeowner or gardener liability in nuisance-based civil lawsuits. Regardless, if records are well kept, they will provide an easy method of tracking the type, rate, and volume of pesticides applied and the success of the management options.

Insect and Mite Pests in Gardens and Landscapes

Aphids and Other Common Sap-feeding Insects

Sap-feeding damage causes leaves to curl and terminal growth to be stunted. In addition, some pest species can transmit viruses. Insecticidal sprays do little to prevent the spread of viruses.
Virtually every plant has at least one aphid species that attacks it. Aphids can be controlled chemically or by natural predators, such as lady beetles. Also, a hard jet of water can blast aphids away from the leaf surface.
Aphids have complicated life cycles that involve winged and nonwinged forms, sexual and asexual reproduction, and primary and secondary host plants. Besides the injury their feeding may cause, aphids also excrete large amounts of a liquid waste called honeydew. Honeydew often provides a site where sooty mold, a black fungus, can grow readily.
Six kinds of aphids plus two types of adelgids and multiple species of whiteflies and mealybugs are the sap-feeding insects most commonly of concern to gardeners.

Woolly Apple Aphid

Eriosoma lanigerum

The woolly apple aphid causes formation of severe galls on the twigs, branches, and roots of flowering fruit trees, pyracantha, mountain ash, and hawthorn. During the summer these aphids often colonize on twig spurs, stems, or old pruning wounds. They produce honeydew and cause conspicuous woolly patches.

Green Peach Aphid

Myzus persicae

Green peach aphids can be found worldwide and have an extensive host range. They can be found on plants both outdoors and in the greenhouse. They overwinter on their primary host, peach and related Prunus species, and then feed on many vegetable and ornamental plants during the growing season. Their feeding can cause stress and reduced growth, but the biggest concern is their ability to spread viruses. These aphids show resistance to many traditional chemicals, so biological control and natural enemies are important in the home garden.

Crape Myrtle Aphid

Tinocallis kahawaluokalani

Crape myrtle aphids feed on only one plant species and do not spread to other plants in the landscape, and some resistance is now available. Like other aphids, they feed on plant sap and can cause leaf yellowing, leaf distortion, leaf drop, and accumulation of sooty mold as a result of honeydew. Always check for infestations on the underside of the leaves. Winged forms (that can migrate to start new colonies) have dark tips to their antennae. The immature aphids have black spikes on their abdomen. Natural enemies can be an aid in reducing populations in mixed landscapes, or insecticides can be used.

Hemlock Woolly Adelgid

Adelges tsugae

The hemlock woolly adelgid is a tiny, aphidlike insect that was introduced into the United States in the 1920s. It is currently in the Smoky Mountains and other counties of East Tennessee attacking eastern hemlock and Carolina hemlock. Adult hemlock woolly adelgids are reddish brown, 1/32 inch long, and are covered in white, cottony secretions. Severe infestations can result in branch dieback and death of hemlock trees. Predatory lady beetles have been released in forested areas to help control the spread of this exotic pest.

Pine Bark Adelgid

Pineus strobi

The pine bark adelgid is an aphidlike pest of white pine. It secretes a white, waxy, cottony covering. It is more of a pest on younger trees with thinner, smoother bark. If you see it, wash off as much of the white, waxy covering as possible and let it dry before treating with an insecticide. Several sprays will be needed over the summer. Thorough insecticide spray coverage is essential for good control. Achieving good coverage is more difficult in tightly sheared trees with dense foliage, such as those found in Christmas-tree farms. The white, waxy covering will become dry and chalky if the adelgids have been successfully controlled.

Whitefly

Multiple species

Whiteflies are common sap-sucking insects that weaken plants and can infest a plant so heavily that they may appear as a cloud if leaves are disturbed. The immobile, immature stages of whiteflies occur on the underside of leaves, so sprays need to be directed to that area if contact is required for control. Both immature and adult whiteflies need to be targeted for control, often with different insecticides. Instances of resistance to common chemical controls have been reported. Therefore, biological controls, soaps, and oils can be useful tools for the management of whitefly populations.

Mealybug

Multiple species

Mealybugs are soft-bodied insects having a fine waxy covering that makes them look like they are covered with flour or meal. A common pest that can affect a range of garden plants, they have two filaments at their tail end. They can move about but like to feed in the leaf axil area. They also produce copious amounts of honeydew.

Scale Insects

Most scale insects fall into one of two types: armored scale or soft scale. Both types secrete a waxy cover, but only the cover of armored scales can be removed to reveal the scale insect beneath. Soft scale produce copious amounts of honeydew while armored scale do not. Scale insects can cause significant damage on houseplants and ornamental plants.

Euonymus Scale

Unaspis euonymi

Euonymus scale is an example of an armored scale. Females are shaped like oyster shells and brown in color; males are elongated and white. The orange-colored nymphs are very small and are commonly called crawlers. Feeding injury causes yellowish spots on leaves. Heavily infested leaves drop prematurely, and branch dieback occurs.
Horticultural oil helps to control scale problems. It is important to target sprays for the crawler stage in April and May and later in the summer, and good scouting is needed to know the best time to spray. Use two sprays about 10 days apart for each flush of crawlers. Before spaying, prune out heavily encrusted branches. In addition, ground-cover euonymus may need to be cut back so the stems are upright, making it easier to get thorough spray coverage.

Crape Myrtle Bark Scale

Eriococcus lagerstroemiae

The crape myrtle bark scale is a relatively new pest that has been occurring on crape myrtles in the United States since 2004 when it was first identified in Texas. ‘It was first seen in Tennessee in 2013 in the Memphis area, and has now been officially reported via EDDMapS in 17 counties across the state as far east as Knox County. The CMBS is neither a hard nor soft scale, but classified as a felt scale, which has a soft felt-like covering and produces copious amounts of honeydew. It can dramatically weaken plants as well as reduce their aesthetic value. Because a large number of crape myrtles are used in Tennessee home landscapes and public plantings, the spread of this pest is concerning. The most effective control option is systemic insecticides applied as a root drench in the spring during the plant’s most active season of growth. Trunk and bark application of systemic insecticides, horticultural oils, and select pyrethroids can be used along with root drenching for quicker control, but are less effective at long-term control when used alone.

Lecanium Scale

Multiple species

Lecanium scale is a soft scale that feeds on sap from several trees and woody ornamentals. Heavy infestations create honeydew and sooty mold issues and can also weaken, stunt, or even kill plants over time. These insects overwinter on the plant in an immature stage and then produce eggs the next year. As with most scales, proper timing of control methods is important to target crawlers that have just hatched and move to the foliage during the spring. Maintaining proper nutrition and reducing stress can also help in addressing these scale pests.

Wax Scale

Ceroplastes ceriferus

The wax scale is a soft scale and has many hosts in the ornamental landscape. It rarely kills plants but reduces their growth and causes plant decline. These insects generally remain on stems and leaves, especially those of the evergreen species such as hollies.

Tuliptree Scale

Toumeyella lirodendri

Tuliptree scale is an example of a soft scale. The waxy covering of soft scales cannot be removed because the cover is firmly attached to the body of the insect. Unlike armored scale insects, soft scale insects produce an abundance of honeydew on which sooty mold may grow. Wait for crawler emergence in late summer before treating with an insecticide. Use dormant oil as a dormant spray in winter or early spring before leaf buds break.

San Jose Scale

Quadraspidiotus perniciosus

The San Jose scale is a hard scale that is an important pest in tree fruit production, feeding on apple, peach, and pear trees. It can damage and kill a tree within a couple of years through infestations on the bark. The sap-sucking insect injects a toxin that discolors an area around the site and causes fruit blemishes that can be used as an indicator of high populations on the trees. Pheromone trapping of the males along with sticky tape can be used to determine the best time to spray to target the vulnerable crawler stage. Often, dormant oil and insecticides are both used at the appropriate time for best control.

Other Sap-feeding Insects

Azalea Lace Bug

Stephanitis pyrioides

Lace bugs, because of their small size, are rarely observed feeding on the underside of the leaves, but their damage is always apparent on the upper leaf surface. Severe feeding injury results in white or yellowish leaf spotting, producing bleached leaves. Another sign of lace bug feeding is the tiny dark spots of lacquerlike fecal material deposited on the underside of leaves. Azalea lace bugs lay eggs on the underside of leaves along the leaf rib. Eggs laid in the fall overwinter and hatch in April. Inspect and spray as needed to control the tiny, black-and-white, spiny nymphs and the lacy-winged adults. Siting is also important because azaleas in hot, sunny locations can be more susceptible.

Fourlined Plant Bug

Poecilocapsus lineatus

The fourlined plant bug feeds on more than 250 host plants, with herbs, mints, and composite flowers being its favorites. Its digestive enzymes attack the glue that holds plant cells together, causing pits where plant cells literally collapse. These dark necrotic spots can fully cover the leaves fed upon and lead to plant wilting. These insects can be captured and crushed by cupping your hands around a branch of the plant and sliding your hands to the tip of the branch.

Squash Bug

Anasa tristis

Squash bugs have mouthparts that can pierce plants and remove sap. Many species in the family feed on seeds, but the squash bug feeds on the stems, leaves, and fruit of crops and kills tissue as well as causing wilting and premature rotting. Pumpkins and winter squash are some of the most common targets.

Leafhoppers

Multiple species of Cicadellidae

Leafhoppers can transmit mycoplasmalike organisms that cause the symptoms known as aster yellows. Feeding by the potato leafhopper can physically damage the leaves, causing them to turn yellow and become stunted. A condition called hopperburn may occur, in which the margin and tip of the leaf turns brown and curls inward.

Spittlebug

Multiple species of Cercopidae

Spittlebugs are closely related to leafhoppers but are differentiated by bubbly fluids that surround the immature nymphs as they feed. Adults may be colorful and look like large leafhoppers.

Leaf-mining Insects

Leafminers are a diverse group of insects that includes flies, beetles, moths, and sawflies. They feed on the soft inner tissue between the upper and lower leaf surfaces, creating serpentine or blotchy leaf mines. (see page 13-13.) Systemic insecticides are the best option for control as mining insects are inside the plant while feeding and would not come into contact with contact insecticides applied to the leaf surface.

Boxwood Leafminer

Monarthropalpus flavus

The adult boxwood leafminer is a small, orange, gnatlike fly and is considered the most serious insect pest of boxwoods. Feeding injury by the yellow larvae causes small, blistered blotches to appear on the leaves. The larvae of this pest spend nearly a year feeding between the top and bottom layer of the boxwood leaves. In April, or about the time weigelas bloom, look for the pupal skins protruding from the underside of the leaves and adult boxwood leafminer flies inserting eggs into the leaves. The eggs hatch in about three weeks and the yellow larvae feed and develop slowly. The first application of insecticide should target the adult leafminer flies. Another treatment of a recommended systemic insecticide should be applied in mid-May (about three to four weeks after adults emerge) to control larvae developing in the new leaves. This species produces only one generation per year.

Caterpillars

Tomato and Tobacco Hornworm

Manduca spp.

These large caterpillars will mature to become a hawk moth but are quite damaging leaf feeders in the immature stage and can quickly defoliate garden (mostly tomato) plants and also damage fruit because of their large size. The tobacco hornworm is more common in southern and Gulf states and the tomato hornworm in northern areas, but their appearance and damage is similar. Insecticides can be used or the biological Bacillus thuringiensis can also be effective. Hand removal is also an option for home gardeners. In addition to these methods, it is not uncommon to see hornworms in the garden that have been parasitized by braconid wasps, as seen in the accompanying photo. These parasitized caterpillars should remain in the garden.

Eastern Tent Caterpillar

Malacosoma americanum

Tent caterpillars are among the earliest springtime defoliators of deciduous trees. They emerge in the spring from egg masses laid on twigs of the host tree. The eastern tent caterpillar can be identified by the white stripe down its back. The forest tent caterpillar has a series of keyhole-shaped spots down its back. Both species produce only one generation per year. Eastern tent caterpillars construct their silken nest at a major branch fork or crotch on the host tree. Forest tent caterpillars construct a silken mat on the trunk or branch of the host tree. During feeding periods, tent caterpillars leave their nests but return to the nest to rest. To control these pests, the webbing needs to be pulled out of the crotch of the tree with a rake or the tree should be sprayed with a recommended insecticide. For optimum effect, the leaves and the webbing should be sprayed, especially when using products that must be ingested to be effective.

Bagworm

Thyridopteryx ephemeraeformis

Bagworm caterpillars feed on more than 128 species of deciduous and evergreen woody ornamentals. In late summer, the maturing caterpillars finish feeding and firmly attach their silken bags to the twigs and pupate. The male moths emerge about four weeks after larval feeding has ceased. They fly around and locate a bag with a female in it, then mate. The female then deposits a mass of eggs inside her bag. The female soon dies, never developing into a winged moth. Treatment is usually required in late May to early June if there are bags on the tree from the previous year. If only a few are found on a tree or shrub, remove the bags by hand.
The adjacent photo shows an immature bagworm just beginning to form a bag. It is approximately 2 cm long and the width of a pine needle.

Fall Webworm

Hyphantria cunea

The fall webworm feeds on almost all shade, fruit, and ornamental trees except conifers. There are two color variations of this caterpillar, one black-headed and the other red-headed. Unlike tent caterpillars, their silken webs are on the ends of branches. Feeding occurs only on the foliage inside the web. The fall webworm has three generations per year in Tennessee. Sometimes the entire host tree will be covered in silk. On young trees, pull or prune out the webbed nests that can be reached and dispose of them as an alternative to insecticide use, and control is seldom recommended in mature well established trees.

Gypsy Moth

Lymantria dispar

Gypsy moths were brought from Europe to Massachusetts in 1868 by a French entomologist who wanted to cross them with silk moths to develop a silk industry in the U.S. They escaped and over the years have spread over millions of acres of forest in the East. Gypsy moth caterpillars can defoliate whole forests.
Oaks are some of their most preferred hosts. Gypsy moth caterpillars feed on more than 200 plants species, including both deciduous and evergreen plants. Every year, pheromone traps are put out to monitor for male moths. Traps are placed all over Tennessee in a grid pattern. If significant numbers of male moths are caught and egg masses found, a decision is made to spray the following spring.

Orange-striped Oakworm

Anisota senatoria

The orange-striped oakworm can be identified by its five orange stripes and a pair of hornlike structures near its head. The horns are sometimes mistaken for antennae. They feed on oak, maple, hickory, birch, and hazelnut trees. Young caterpillars feed on entire leaves except for the veins. Older caterpillars eat all but the main leaf vein as they defoliate one branch before going on to another. Mature caterpillars crawl away from trees and pupate in the soil. The caterpillars can be shaken from branches and stepped on.

Yellow-necked Caterpillars

Datana ministra

Yellow-necked caterpillars feed in groups on a wide range of hosts, including crabapple, cherry, almond, quince, maple, elm, butternut, walnut, oak, hickory, and locust trees. Hatching from clusters of eggs laid on the underside of leaves, young yellow-necked caterpillars chew off outer leaf areas, but as they begin to grow they consume the entire leaf. The caterpillar gets its name from the bright orange-yellow segments behind its head. Fully grown caterpillars crawl down the trunk and burrow into the soil to pupate. There are two color phases: red with yellow stripes and black with yellow stripes. The caterpillars can be shaken from the branches and stepped on as a mechanical means of control.

Beetles: Leaf- and Fruit-feeding

Colorado Potato Beetle

Leptinotarsa decemlineata

This black-and-yellow-striped beetle is quite familiar to home gardeners and is likely the most serious pest of Irish potatoes. These adult beetles overwinter in the soil and then emerge to feed and lay eggs. The hundreds of eggs that each female can lay soon hatch, and the immatures begin feeding on potato leaves. Two or even three generations can occur per year. The Colorado potato beetle is now developing some resistance to common chemicals, so using different classes of chemicals, biological control, or even physical control is recommended.

Japanese Beetle

Popillia japonica

Japanese beetle adults feed on a wide range of trees, shrubs, and vines. They feed between the leaf veins, giving the attacked foliage a skeletonized appearance. Japanese beetles were first found in the US in 1916. To protect foliage, target adults feeding on susceptible ornamentals. Japanese beetle traps are not recommended because they attract this pest to the yard, where the short-lived adults then lay eggs in turfgrass soil where the larvae and pupae develop and emerge as adults the following spring and early summer.

Mexican Bean Beetle

Epilachna varivestis

This species of beetle is actually a ladybird beetle and is a rare plant pest in that family. Adults and immatures feed on bean leaves. The larvae often feed in a way that removes the top layer of leaf tissue and leave a leaf skeleton while adults feed on all leaf tissue except the veins.

Tortoise Beetles

Multiple species of Chrysomelidae

Tortoise beetles feed on leaves and overwinter as adults in protected locations under debris or bark. They then emerge in the spring to feed and lay eggs. Several generations may occur each year, and feeding damage occurs from both adults and larvae. They can be identified on the basis of the broad wing covering that is often transparent or nearly so on the edges. One common species feeds on the foliage of morning glory and sweet potato.

Plum Curculio

Conotrachelus nenuphar

Also called a weevil, the plum curculio is a beetle with a snout. The adult beetles feed and lay eggs in maturing fruit. Plum, apple, apricot, peach, nectarine, quince, cherry, and pear trees can all be hosts. The wounds caused by this insect scar and cause distorted growth as the fruit develops. Early fruit drop can also occur.

Southern Pine Beetle

Dendroctonus frontalis

The Southern Pine Beetle is one of the most destructive insect pests of pine in Tennessee. Indications of infestation include browning of needles, presence of pitch tubes, S-shaped feeding galleries underneath the bark, and round exit holes.

Sawflies

Sawflies may look like moth or butterfly caterpillars, but they are actually the larvae of small nonstinging wasps. To distinguish between sawflies and caterpillars, examine the legs. Sawfly larvae have more than five pairs of prolegs (generally eight) and caterpillars have two to five pairs of prolegs. Sawflies and caterpillars are controlled by different methods, and thus it is important to be able to distinguish between them.

Red-Headed Pine Sawfly and Other Conifer Sawflies

Multiple species

The introduced pine sawfly, originally from Europe, is a common pest of white pine and several other pines. Numerous other conifer sawfly species are pests of other conifers. The female sawfly damages plants by using her sawlike ovipositor to saw slits in plant material to lay eggs. Conifer sawflies, in the first larval stage, damage plants by eating only the outer portions of the needles and then later the entire needle.

Rose Slug

Multiple species

The rose slug is a sawfly pest that skeletonizes the leaves of roses. Common sawflies that feed on deciduous plants comprise a large group of more than 800 species. This large group does not feed on conifers but feeds on a variety of other trees and shrubs.

Pin Oak Sawfly and Slug Oak Sawfly

Multiple species

The pin oak sawfly is a pale green color with a tan head. Slug oak sawflies are somewhat sluglike in appearance. They tend to chew off only the top layer of the leaf in their early larval stages.

Clearwing Borer Moths

The clearwing borer moths are day-flying insects. They lay their eggs on or near the bark of their host trees. The resulting larvae chew through the bark or enter through cracks and crevices in the bark. All of these clearwing borers (the dogwood borer, peachtree borer, rhododendron borer, lesser peachtree borer, lilac or ash borer, and banded ash clearwing) stay in the tree as larvae for about a year, except for the oak borer, which stays in oak trees (especially pin oaks) for almost two years. A protective insecticide spray should be applied to the trunk and to the main scaffold branches before the larvae have a chance to hatch from their eggs and enter the tree, and scouting and the use of pheromone traps is needed to determine timing.

Dogwood Borer

Synanthedon scitula

The dogwood borer is found wherever flowering dogwoods are grown. Female moths lay eggs next to wounds and breaks in the bark, on the trunk, and on the limbs. Newly hatched larvae enter through wounds, calloused areas, cankers, or some other break in the bark. Sap stain and fine frass (insect excrement) on the trunk and branches as well as loose bark indicate borer activity. Badly infested trees usually appear unhealthy and may exhibit dieback in parts of the crown. There is usually one generation, with adults emerging over an extended period from late April to mid-October. To help prevent infestation by dogwood borers, take special care not to wound the tree trunk with a weed eater or lawn mower. Mulching around the tree should reduce this type of damage. Also, a protective insecticide spray can be applied in late April, mid-July, and early September.

Rhododendron Borer

Synanthedon rhododendri

The rhododendron borer can cause the plant to become girdled around the base and also have tunnels throughout. To control, spray in mid-May and late June.

Peachtree Borer

Synanthedon exitiosa

Female peachtree borer moths lay eggs on the lower trunk of Prunus spp. or on weeds, grass, debris, and bare soil around the trunk. Eggs hatch in about a week and the larvae immediately burrow through the bark into the sapwood of the tree. Wounds and breaks in the bark are not needed, as the larvae are capable of chewing directly through the bark. Large masses of gum and particles of bark and frass at the base of the plant are evidence of an infestation. There is usually one generation, with adults emerging over an extended period that may range from late spring to early fall. Protective insecticide sprays can be applied in late April and again in mid-June.

Lesser Peachtree Borer

Synanthedon pictipes

This pest tends to attack the branches of trees already weakened by the peachtree borer.

Lilac-Ash Borer and Banded Ash Clearwing Borer

Podosesia syringae and P. aureocincta

The lilac-ash borer emerges in April. Therefore, to control, spray lilac, privet, fringe tree, and mountain ash in mid-April and mid-June. The banded ash clearwing moth comes out in August. These clearwing borer moths mimic paper wasps. To control, spray the trunk and scaffold branches of ash trees in mid-April and again in mid-July.

Squash Vine Borer

Melittia curcurbitae

Summer and winter squash along with pumpkins are common targets for the squash vine borer. This clearwing moth spends the winter in the soil as a larva or pupa and then emerges the next spring. Eggs are laid and glued to the stem base of host plants where larvae can bore into the stem for feeding, which causes plant wilting and reduced yield or plant death.

Root Collar Borer

Euzophera ostricolorella

The root collar borer caterpillar is not in the clearwing moth family. It affects yellow poplar (tuliptree), generally by attacking the base of the tree. It is common to see excrement as well as a dark ooze and bark that is cracked or loose. Protective sprays are often applied in both early May and early September.

Wood-boring Beetles

Several types of wood-boring beetles can affect landscape and fruit trees in residential plantings. Metallic wood-boring beetles are probably the most damaging pest of trees in the nursery and the landscape. The adults are slightly flattened and often have a metallic sheen. Of the nearly 700 North American species, most prefer weakened, injured, dying, or recently dead trees, but a few species attack healthy trees. Newly transplanted ornamental trees and shrubs are particularly susceptible to attack.
Larvae usually feed and create winding tunnels just under the bark, which may girdle and kill the tree. The larvae of metallic wood-boring beetles are called flatheaded borers because of the flattened enlargement just behind the head. Areas of bark where injury has occurred often appear darkened and somewhat sunken. They may later split above the injury. Severely injured trees may have large areas where the bark has fallen off. D-shaped or oval exit holes in the bark indicate where mature adult beetles have emerged.

Flatheaded Apple Tree Borer

Chrysobothris femorata

The adult flatheaded apple tree borer is ½ inch long. Infested trees appear unproductive, usually with a loss of many leaves in the terminal. Newly planted trees are especially susceptible to attack by these pests. Insecticide treatments are advised in early-May and mid-June through at least the third year after transplanting, giving the plants protection until they become well established and are growing vigorously.
Host plants include maple, linden, oak, sycamore, tulip tree, willow, cotoneaster, apple, pecan, hickory, cherry, walnut, poplar, beech, elm, hackberry, mountain-ash, serviceberry, hawthorn, redbud, horse chestnut, persimmon, and boxelder.

Twolined Chestnut Borer

Agrilus bilineatus

The larva of the twolined chestnut borer is ½ inch long. After an initial spray in early May, make a second application in mid-June. Insecticide treatments through at most the third year after transplanting will protect the plants until they are well established and growing vigorously. If spring and early summer drought conditions occur and irrigation is not possible, preventive insecticide treatments are advised on older oak, beech, and chestnut.

Emerald Ash Borer

Agrilus planipennis

The emerald ash borer, a metallic wood-boring beetle, is thought to have entered the US in packing material. It was reported in 2002 attacking ash trees in Michigan. Emerald ash borer larvae feed and create winding tunnels just under the bark, girdling and killing the trees. These borers have killed green ash, white ash, and black ash as well as several horticultural varieties of ash. The emerald ash borer has been found in Tennessee, having moved in from other parts of the eastern United States. This pest will kill all unprotected ash trees in the US.

Longhorned Beetles and Roundheaded Borers

Multiple species of Cerambycidae

Longhorned beetles vary in size and color, but their very long antennae are characteristic of most species. More than 900 species of longhorned beetles exist in North America, with some 230 species that can be found in Tennessee. Only a few species seriously damage living trees. Weakened, injured, dying, or recently felled trees are usually attacked. The most harmful species bore into the heartwood and cause defects that seriously degrade lumber.
The larvae of longhorned beetles are called roundheaded borers because they make round exit holes in the wood and bark. All parts of the tree may be attacked, including terminal shoots, branches, trunk, and roots. Some species require two to three years to complete their life cycle. Tunneling into the heartwood by the larvae may structurally weaken trees.

Southern Pine And Carolina Sawyers

Monochamus titillator and M. carolinensis

Sawyer beetles are roundheaded borers that attack stressed or weakened pines and are often referred to as a secondary pests. The exit holes in the trunk are circular and the diameter of a pencil.

Asian Longhorned Beetle

Anoplophora glabripennis

The Asian longhorned beetle is thought to have entered the US in wooden crates and pallets shipped from China. Adult beetles were found in New York City in 1996 and in Chicago in 1998. Numerous species of hardwood trees are susceptible to attack, with maple being a preferred host. Millions of dollars have been spent to remove thousands of trees and carry out other eradication efforts to help prevent the spread of this exotic pest. The largest infestation currently in the U.S. is in Clermont County, Ohio. As of 2016, the Asian longhorned beetle is not in Tennessee.

Locust Borer

Megacyllene robiniae

Adult locust borers are active when goldenrod blooms. They are a pest of black locust. Extensive tunneling by this pest can weaken trees enough that they may break in windstorms.

Cottonwood Borer

Plectrodera scalator

The cottonwood borer, a native insect, could easily be mistaken for the Asian longhorned beetle. The Asian longhorned beetle has small white markings on a black body, whereas the cottonwood borer has black markings on a white body. These insects feed on cottonwood, other poplars, and willows. The larvae attack the roots and the base of the tree. They can girdle young trees. Adults feed on petioles and tender shoots.

Bark Beetles and Ambrosia Beetles

Bark beetles feed just under the bark in the cambium. Their feeding by larvae and adults can girdle trees, causing branch dieback or death of the tree. Ambrosia beetles tunnel much deeper into the wood where the adults make clean brood galleries to lay their eggs. The larvae feed on ambrosia fungi that is introduced into the galleries by the excavating adults.

Ips Beetles

Multiple species of Ips

Primarily attacking pines, Ips beetles cause large losses in timber in the South. They often feed on the phloem of weak and dying trees or those that have been recently cut. In addition to being prevalent in logging areas, they can also move in after a storm or some other natural event has caused severe damage to trees.

Granulate Ambrosia Beetle

Xylosandrus crassiusculus

A small, 3-mm ambrosia beetle that came from Asia, the granulate ambrosia beetle can be a serious threat to many ornamental and fruit trees and shrubs, but it does not feed on conifers. These beetles actually feed on a white symbiotic fungus that they introduce into their tunnels in the tree rather than the wood itself. Frass being pushed out of the galleries is a common sign of infestation, and it us usually seen in the early spring, often while the plants are still dormant.

Other Damaging Insects

Thrips

Multiple species of the order Thysanoptera

Thrips are tiny, slender-shaped insects that hide in the folds of the leaf sheath and are attracted to flowers. Thrips are sap feeders but access plant fluids in a manner called rasping-scraping; they essentially remove the epidermis of the leaf. To monitor for thrips, leaves should be breathed on; this action will cause the thrips to become active and easy to see. Blue or yellow sticky traps can be used as a monitoring tool. Thrips themselves can move quickly and can be a challenge to see with the naked eye. Leaf and flower distortion as well as the characteristic injury and small dots of excrement shown in the adjacent image are good indicators.

Apple Maggot

Rhagoletis pomonella

The apple maggot is in the fruit fly family and overwinters in soil as a pupa. Adults emerge in summer and produce small puncture wounds in the fruit as they lay eggs. However, the greatest damage is from the young maggots (immature flies) that tunnel through the fruit.

Spottedwing Drosophila

Drosophila suzukii

A vinegar fly, the spottedwing drosophila lays eggs in unripe as well as ripe fruit. The result is that larvae can be present in fruit that would otherwise be quite edible. Small fruit, including raspberries, blackberries, grapes, blueberries, and strawberries, have been affected, but soft-skinned tree fruits could be attacked as well.

Mites

Spruce Spider Mite and Southern Red Mite

Oligonychus ununguis and O. ilicis

Mites are not true insects. However, they are related to spiders and ticks. Mites have tiny mouthparts modified for piercing individual plant cells and removing the contents. The spruce spider mite is a pest of conifers, while the southern red mite is found on Japanese holly, camellia, azalea, laurel, rhododendron, boxwood, and other hollies.
These are primarily cool-season mites that are active in the spring and fall. Feeding injury causes light-colored flecks on foliage, with infested trees displaying a yellowish or grayish appearance. Heavy feeding injury may result in premature needle drop. Eggs overwinter on the plant. When temperatures consistently exceed 86°F for several days, populations decline and many eggs go into summer dormancy. With the return of cool weather, new populations of mites emerge from the dormant eggs.
When checking for southern red mite, use a hand lens to inspect the underside of the leaves for the reddish eggs and mites. Also, sample in the early spring and fall by holding a sheet of paper on a clipboard under a branch and striking the branch or leaves to dislodge mites. Treat if mites are detected. Use horticultural oil — summer oil — as a dormant or summer spray. A dormant application targets the overwintering eggs. Some plants such as cryptomeria, some azaleas, and several other plants are sensitive to oils, while Japanese holly, savin junipers, spruces, and Douglas fir tend toward oil sensitivity. Do not use oils on oil-sensitive plants. Recommended miticides can also be used, primarily for active stages.

Twospotted Spider Mite

Tetranychus urticae

Twospotted spider mites reproduce quickly in hot, dry, dusty conditions and produce lots of webbing. Spider mite infestations are especially common on houseplants and in greenhouses. The mites overwinter as adults in weeds close to the ground. Consequently, a dormant spray for eggs is not useful for these pests. Instead, it is necessary to wash the dust and some mites off the plants periodically with a garden hose, especially during hot, dry periods. This pest has a wider host range than any other mite and infests ornamentals and edible crops. The mites are active from earliest spring to late fall. Feeding injury causes the foliage to yellow and become dry and brittle. Premature leaf drop occurs on heavily infested plants.

Turf Pests

Scarab Beetles

Multiple species

There are many species of scarab beetles. Some of the most commonly recognized ones are May and June beetles, Japanese beetles, northern masked chafer, southern masked chafer, and black turfgrass ataenius. These pests are most active during the spring and summer months. The larvae of scarab beetles are called white grubs and are major pests of turfgrasses.

Sod Webworms

Multiple species

Sod webworms are caterpillars that feed on the blades of grass. They are light-colored with dark spots and they make silk tunnels in the grass. Check for sod webworms by preparing a soap solution of 2 teaspoons of liquid dishwashing detergent in a gallon or two of water. Pour this solution over a 4-square-foot area. If more than four sod webworms are found, the landscape should be treated.

Cutworms

Multiple species

Cutworms are dark, dingy-colored caterpillars that feed at night and hide in the ground in daylight. They clip off the blades of grass at the crown. Treat when one or more cutworms are found per 4 square feet of turf. Check for cutworms using the same method used for sod webworms.

Armyworm and Fall Armyworm

Multiple species

These caterpillars can reach high population levels and can totally defoliate fields or yards. They can also be detected by using a soap solution flush. Sample periodically throughout the spring and summer and treat when any populations of these caterpillars are detected.

Slugs and Snails

Slugs and snails can be garden pests in dense foliage where the environment is moist and humidity is high. Both animals feed mainly at night. They chew irregular holes with smooth edges into leaves and flowers, and they can clip succulent plant parts. They also chew fruit and young plant bark.
Slugs are fleshy, slimy members of the phylum Mollusca and are similar in structure and biology to snails. However, slugs lack the snail’s external, spiral shell. These mollusks move by gliding along on a muscular “foot.” This muscle constantly secretes mucus, which facilitates their movement and later dries to form the silvery “slime trail” that signals the presence of either pest. Both species prefer cool, moist hiding places during the day.
Sanitation is important for control of slugs and snails. Susceptible plants should be kept free of plant debris (such as leaves and pulled weeds), old boards, bricks, or stones that provide cool, moist hiding places. Barriers of diatomaceous earth, lime, sawdust, copper stripping, and salt-embedded plastic strips can be used around plant benches in greenhouses. Some types of barriers such as diatomaceous earth can be used around individual plants. Bait pellets, handpicking, traps, barriers, and natural predators can be used for slug and snail control on ornamentals. However, do not allow pellets to come in contact with plants. Outbreaks of insect pests in home gardens often occur because there are not enough natural enemies to control the pests. The types of natural enemies that play the greatest role in keeping pests in check are predators, parasitoids, and disease-causing organisms. These natural enemies are found on a wide variety of crops where the pests are found. It is important to be able to recognize these beneficial organisms and not mistake them for destructive pests needing control.

Butterfly Gardening

One of the joys of having a garden is being able to observe the interrelationships among plants and insects. Insects use nectar as a source of carbohydrates and pollen as a source of protein. A butterfly garden is a great way to observe the dynamics of nature. The garden should be designed to include a variety of plants that bloom from early spring throughout the fall. Examples of suitable plants include parsley, carrots, Queen Anne’s lace, dill, fennel, marigold, buttonbush, and purple coneflower. They provide many types of insects with the nectar and pollen they need for their growth and development. A healthy backyard ecosystem is attractive to many types of phytophagous insects, parasitoids, and predators. The regulatory effect of these natural enemies tends to bring more stability to the ecosystem, which often results in fewer and less severe pest outbreaks.

Beneficial Arthropods and Microorganisms

Predators

The most common predators in gardens are beneficial insects and spiders. Predators actively seek, kill, and consume a large part of another insect, mite, or other arthropod. Common predators are lady beetles, ground beetles, lacewings, praying mantids, damsel bugs, and spiders.
Several mail-order businesses advertise predators for sale. Release of these beneficial insects into a garden rarely leads to pest suppression because the insects quickly disperse in search of additional food. Also, in many cases a number of these insects are already present in the garden. Maintaining a complex landscape with many types of plants and habitats helps attract predators and other beneficial arthropods. Therefore it is important to understand and teach others to distinguish the beneficial insects from the destructive ones.

Lady Beetle

Multiple species

Adult lady beetles, commonly called “lady bugs” or “ladybird beetles,” are oval-shaped insects that vary in color but usually have black or orange-red spots on their wing covers. Lady beetle larvae are spindle- or carrot-shaped with conspicuous warty or spiny backs. They usually are black, blue, and orange with thick, stubby legs. Both the lady beetle adults and larvae feed on small, soft-bodied insects (like the damaging aphids) and insect eggs.
Lady beetle eggs are yellow to orange and laid in a cluster of 5 to 20 eggs. They are found standing on end in contact with one another. All stages of lady beetle development are usually found feeding on their prey from spring to fall on the foliage of plants. The photo at the lower right shows a lady beetle larva feeding on aphids.
Asian lady beetles hibernate in cooler months, though they become active whenever the temperature reaches about 50°F (10°C). Because the beetles use crevices and other cool, dry, confined spaces to hibernate, significant numbers may congregate inside walls if given a large enough opening. These beetles are attracted to sunlit buildings in late October afternoons. They can aggregate by the thousands each fall and find their way inside through cracks and crevices. During the winter, they congregate indoors in sunlit areas because of the heat available, so even on fairly cold winter days some of the hibernating beetles become active. These beetles can form groups that tend to stay in window corners. This beetle has been also found to be attracted to dark screening material for its warmth.

Ground Beetle

Multiple species

Ground beetle adults are flat in shape, long-legged, and swift-running. While many species are black or brown, sometimes the colors are brilliant metallic greens, blues, or purples, occasionally spotted with iridescent dots or pits of gold. The adults range in length from ½ to 1½ inches. Ground beetle larvae are dark-colored, slender, a little flat and slightly tapering to the tail, which terminates in two bristly, hairlike or spinelike structures. Both the adults and larvae feed on small, soft-bodied insects, eggs, and caterpillars. Ground beetle adults and larvae are generally found on the soil, acting as ground-level predators.

Lacewing Predators

Multiple species

Lacewing adults are insects having many veins in their wings, giving them a netlike appearance. The wings are held rooflike over the back. The adults are green or brown, and some have characteristic golden-colored eyes. Lacewing larvae are about ½-inch-long, spindle-shaped insects with long, sharply pointed mandibles. (see adjacent photo.) The mandibles protrude from the front of the head and allow the larvae to suck dissolved juices from their prey. These larvae are tan and white with a warty or spiny appearance. Lacewings eat small, soft-bodied insects, eggs, and caterpillars. Lacewing eggs are small, green to whitish, laid at the end of a slender, threadlike stalk.

Praying Mantids

Multiple species

Praying mantids are green or brown with long bodies and papery wings. Three species are present in Tennessee. These medium to large insects are readily recognized by the enlarged front legs that they use for grasping their prey. Eggs are laid in a mass, arranged in a definite pattern of rows, and glued together. The egg case of the Chinese mantid is tan and looks like a small polystyrene foam block about the diameter of a golf ball. The egg mass is rather commonly observed glued to branches of trees, fence posts, or other objects. The winter is spent in the egg stage. Only one annual generation of these insects has been observed. The praying mantid has often been given too much credit as a predator, perhaps because of its size and menacing look. Praying mantids generally wait for the prey to come to them. They are often found waiting next to flowers that attract pollinators or other beneficial insects. Thus they often feed on both beneficial and pest insects.

Damsel Bug

Multiple species

Damsel bug adults are long, slender, cigar-shaped insects. They are tan to brown and about ½ inch long. The wings have a light smoky hue. The front legs are thick and are made for grasping and holding prey. Damsel bug nymphs resemble the adults except that they have no wings and appear very fragile. Both the adults and the nymphs feed on small, soft-bodied insects, caterpillars, and eggs.

Spiders

Multiple species

Spiders are not insects, but these arthropods are very important as predators of insects in the garden. Many types of spiders are found in the garden, and they vary greatly in size and color. They will prey on almost any insect that comes within their range. There are generally large numbers of spiders in the landscape or wherever insects are found.

Parasitoids

Parasitoids live in or on their host to feed and weaken or kill it. Some types of nematodes, called entomopathogenic nematodes, attack and kill insects. Many of the more common beneficial insects are more specifically referred to as parasitoids because their immature stages are parasitic, but they are free-living as adults. Wasps and flies are some of the most common orders of insects that can act as parasitoids, as their young feed inside the bodies of other insects and eventually kill them. Although some of these parasitoids are commonly purchased and released in greenhouse production, it is more common to practice conservation measures to support natural populations in landscapes and gardens.

Braconid Wasps

Multiple species

Some of the parasitoids most commonly observed in home gardens are braconid wasps, which lay eggs in the body of tomato and tobacco hornworms and other caterpillars. The eggs of this parasitoid hatch into larvae that riddle the internal organs of the hornworm during development. The parasitoid larvae exit from the back of the hornworm and spin their cocoons just prior to pupation. As pupation occurs, the parasitoid can be observed as white cocoons on the back of the hornworm. These are often mistaken for hornworm eggs by the gardener and consequently destroyed. However, effort should be made to preserve these pupae since the adult parasitoids will emerge from them to continue their beneficial activities.

Tachinid Flies

Multiple species

This family of flies is one of the most important in providing biological control. Their larvae can act as internal parasites of the immatures of several different beetles, moths, sawflies, grasshoppers, and true bugs. The many different species of tachinid flies can be relatively host specific or may parasitize multiple hosts. The eggs of these different species enter the host differently; they can be ingested or inserted by the female into the host. However, in all the pests that they can parasitize, the maggots feed internally on the host and then emerge to pupate.

Pathogens (Biopesticides)

Microorganisms pathogenic to insects — known as entomopathogenic microorganisms — can include protozoa, bacteria, fungi, and viruses. In the landscape and garden, pest arthropods are commonly subject to natural mortality from bacteria, such as Bacillus popilliae (milky spore); fungi, such as Beauveria bassiana; and viruses, such as gypsy moth and tent caterpillar NPVs (nuclear polyhedrus virus).
These entomopathogens are also valuable components in landscape and garden IPM. The most commonly used biopesticide materials applied to control garden insect pests are bacteria and fungi. Commercial products often use subspecies of Bacillus thuringiensis (Bt) to control a range of pests. Dipel and Thuricide are products containing Bt subspecies kurstaki to control a number of caterpillars, including hornworms and cabbage loopers. There are also subspecies that can be used to control mosquitoes and some beetles. Beauvaria bassiana is a fungus used in the formulation of Mycotrol and BotaniGuard that can infect and kill soft-bodied insects, such as aphids and thrips. Once established, the survival of biological control agents is dependent on successfully integrating them with other management strategies because the use of some fungicides and other plant disease control materials can kill these entomopathogens.

Summary

Insects can have a major effect on the success or failure of a garden or landscape. To ensure that insects support rather than destroy the garden, it is crucial to understand the basic biology, anatomy, and function of insects in our lawns, gardens, and landscapes. By understanding the difference between beneficial and harmful insects as well as understanding how insects grow and develop, gardeners can learn to work with and not always against garden insects.
Integrated pest management (IPM) is a multifaceted approach in which the damage of the uncontrolled pest is compared with the cost of treatment and the effect of control tools on nontarget organisms. IPM considers the damage of the uncontrolled pest compared with the cost of treatment and nontarget effects of control tools. With the increasing restrictions on pesticide use, it is more important than ever to teach gardeners the various IPM strategies. Key elements are knowing how to scout for pests and understanding a range of strategies for controlling them. For long-term success it is also essential to assess and record the results of management actions as a guide for future pest management decisions.