University of Missouri Extension

IPM1020, New June 2003

Turfgrass and Insects

Link to PDFBrad Fresenburg
Department of Horticulture
Bruce Barrett
Department of Entomology
Fred Fishel
Department of Agronomy

While insects are one of the most populous forms of animal life on earth, only a small number of insects may, at some time, become a potential problem in turfgrass. Turfgrass insects can be somewhat cyclical and very dependent on a number of factors. Weather, suitable food sources, desirable habitat and predators all play a part in the population size of particular insect species.

Turfgrass damage is usually not observed until the numbers of an insect species reach a threshold level. For example, a homeowner does not need to treat a lawn with pesticides if only one or two white grubs are found while doing yardwork.

However, if the homeowner peels back dead sod and finds more than five annual white grubs per square foot, the homeowner would need to treat. The presence of insects may always exist but not always at damaging levels.

Turfgrass pests cannot be controlled over long periods of time solely through the use of pesticides. To have healthy and vigorous turfgrass, it may be necessary to use pesticides in combination with sound cultural practices. A properly designed integrated pest management (IPM) system not only will maintain control of existing pests, but also will help prevent the recurrence of these pests and the possibility of new pest outbreaks.

You should plan for possible pest problems before you plant. Keep records of problems in your lawn(s) and talk to neighbors about pest problems they have experienced.

A healthy, growing plant is the best defense against most insect pests. Many plants become more susceptible to pests if they are stressed. Following good turf management practices with mowing, proper watering, fertilization, aeration, thatch control and overall sanitation (leaf litter, mulches and other debris) produces good, healthy, dense turf.

University of Arizona photoIntegrated pest management for insect control
Integrated pest management, the idea of integrating turf management cultural practices into a control program for turfgrass pests, is a concept that has been around for years. Efforts to start an IPM program begin with a discussion of basic plant health care.

More detailed discussions about turfgrass species/cultivars, mowing, watering, fertility, aeration and thatch control are all part of this newer concept to put more emphasis on plant health care (PHC). What can you do to develop the healthiest plant possible to combat or defend against weeds, diseases or insects?

IPM and PHC both still recognize the need for insecticides when all else fails. There are times when insect levels are just too great for even a healthy lawn to overcome. Turfgrass managers adopting IPM or PHC practices will have a better understanding of what environmental conditions weeds, diseases and insects prefer.

When pest problems prevail, did the turfgrass manager do all that was culturally possible, or is there something that could have been added or changed in the management program? Critical decisions early in the development of a pest management program can make a significant difference in the direction a program takes.

Turfgrass species and cultivars

If possible, select a species, cultivar or blend/mixture of turf that is best suited for the environmental conditions it will be grown under and keep it growing vigorously. Turfgrasses adapted to Missouri's transitional climate are better able to withstand stress. Keep in mind, though, we do not have a single turfgrass species that will grow well year-round.

However, we have opportunities to select turfgrass species that offer some insect resistance. Turfgrass species have a natural resistance because some insects prefer one species of grass over another species. Selecting endophyte-enhanced turfgrasses is another means of growing a healthy stand of turfgrass that can reduce pesticide use.

Crop Science Society of America photoEndophytes are fungi (Neotyphodium spp.) that live within turfgrass plants. Endophyte-enhanced turfgrasses (perennial ryegrasses and tall fescues) resist insect damage by producing toxins called alkaloids. These alkaloids are not harmful to plants but deter insects that feed on them.

Although ants do not cause direct turf damage, ant mounds reduce turfgrass density. This becomes more problematic on closely mowed golf greens.

Mowing

Turfgrasses are placed under constant stress when they are mowed too close. Scalping reduces plant vigor and reduces overall root growth, which makes the plant more susceptible to other environmental stresses.

Keep turfgrasses mowed to a recommended height (never removing more than one-third of the leaf blade at one time) and always keep mower blades sharp. Cool-season turfgrasses can be maintained from 2 to 3-1/2 inches, while warm-season grasses should be maintained at 1-1/2 inches or less. Proper mowing practices will make a lawn more tolerant of insect damage.

Watering

Irrigation becomes a vital part in the development of a healthy lawn; however, watering could have some drawbacks when insects are involved. Beetles of many root-feeding insects prefer moist soil in which to lay eggs. Egg-laying females will seek out moist soils to lay eggs, since the survival of their larvae (white grubs) are dependent on moisture.

Allowing turfgrasses to dry out slightly during the peak flight period (late May to early June) may be beneficial to reduce the potential for white grub damage in late July to early August.

Good irrigation practices will help turfgrasses recuperate in late summer and early fall. Sound irrigation practices also encourage a vigorous root system, and therefore a healthier top-growth. Maintaining a healthy turf will help mask damage caused by other insects, such as billbugs and sod webworms.

When irrigating, avoid puddles and runoff. Most clay soils in Missouri have an infiltration rate of around 1/4 inch per hour. Determine the output of your irrigation system by placing small cans at various spots in your lawn.

Simply match the output of your irrigation system to the infiltration rate of your soil. Your irrigation system may only need to run 20 minutes to equal the infiltration rate of your soil type. Applying more water than the soil can absorb is a waste.

Fertility

Soil testing is the best start in developing a good fertility program. Avoiding excessive nitrogen applications will keep plants from becoming to succulent and therefore more susceptible to insect damage. Excessive fertilizers also can lead to significant thatch layers, which make a good habitat for chinch bugs, billbugs and sod webworm.

Following local recommendations for a balanced fertility program will provide good shoot and root growth and can provide good recovery from light to moderate insect damage.

Aeration

Aeration (hollow or solid tines) can greatly improve the quality of turfgrasses. Aeration reduces compaction and allows air, water and nutrients to more readily enter the root zone of turfgrasses. Creating a better root-zone environment will increase the quality of shoots and leaf tissue by several times. At the proper times of the year, aeration for your turfgrass species will make more efficient use of water and fertilizers applied to your lawn.

Soil removed due to core aeration (pulling plugs of soil) will add soil into the thatch layer of your lawn, which, in turn, allows soil microbes to break down organic matter in the thatch. Little to no thatch development will discourage some insects from inhabiting your lawn.

Thatch

Thatch is the buildup of dead and living stems and roots between the green stems or leaves and the soil surface. Thatch layers thicker than 1/2 inch can reduce water and nutrient movement to the soil and give insects a perfect habitat for laying eggs.

Thatch layers can be controlled by several ways. For example, the use of a core aerator, as previously discussed earlier in the guide, is one way to control thatch layers. Also, soil microbes in soil brought to the surface of the thatch layer will break down organic matter. Light topdressings with topsoil will provide the same results as well. An active earthworm population also will provide some decomposition of organic matter and thatch.

Mechanical removal of the thatch layer can be accomplished with a de-thatching or vertical-slicing machine. These machines can be rented at a local hardware or rental store. Set the depth of the blades just low enough to catch the soil surface. By doing so, the entire thatch layer is sliced away along with incorporating some soil into the remainder of the thatch layer.

Good plant health care practices are the key to developing a vigorous lawn. A healthy lawn can withstand two to three times the normal insect threshold for economic damage and offer a quick recovery when damage does occur.

Insect anatomy
All adult insects have two physical characteristics in common. They have three pairs of jointed legs and three body regions: a head, thorax and abdomen.

Head

The head has antennae, eyes and mouthparts. Antennae vary in size and shape and can be helpful in identifying some pest insects. Antennae are movable and contain sensory receptors that are used to detect odors, tastes, vibrations and other stimuli. Insects have compound eyes composed of many facets, each with its own lens. Compound eyes enable insects to detect motion but probably do not produce clear images.

Most insects also have one to three simple eyes (ocelli) located on the upper part of the forehead. These simple eyes do not see images, but they are sensitive to changes in light intensity that may trigger a reaction of flight or running.

The four general types of insect mouthparts are chewing, piercing-sucking, sponging and siphoning. Chewing mouthparts contain toothed jaws that bite and tear. Beetles, caterpillars (larvae of Lepidoptera, including armyworms, cutworms and sod webworm) and grasshoppers are in this group.

Piercing-sucking mouthparts consist of a long, slender tube that is forced into plant tissue to suck out juices or sap. Insects with these mouthparts include chinch bugs, greenbug aphids and spittlebugs. Mites, which are not insects, also have piercing-sucking mouthparts.

Sponging mouthparts are tubular tongue-like structures with a spongy tip to suck up liquids or soluble food. This type of mouthpart is found in house flies. Siphoning mouthparts are formed into a long tube for sucking nectar. Butterflies and moths have this type of mouthpart.

Thorax

The thorax contains the three pairs of legs and (if present) the wings. The various sizes, shapes and textures of wings help identify insect species. The forewings take many forms. In beetles, they are hard and shell-like; in grasshoppers, they are leathery.

The forewings of flies are membranous; those of true bugs are part membranous and part hardened. Most insects have membranous hindwings. The wings of moths and butterflies are membranous but are covered with scales.

Abdomen

The abdomen is usually composed of 11 segments, but eight or fewer segments may be visible. Along each side of most of the segments are openings (called spiracles) through which oxygen enters and carbon dioxide exits the internal respiratory system.

Near the end of the abdomen is an opening, the anus, through which waste passes from the insect's body. In some insects, the tip end of the abdomen has tail-like appendages. It is on the abdomen of white grubs where raster (hair) patterns identify one species of white grub from others.

See rasters

Cutworm damage

Cutworms feed on turfgrass crowns, which produces thinned, tan-colored spots around tunnel entries. Birds on golf greens usually indicate the presence of cutworms.
 

Species of white grubs

White grubs are the primary insect problem many homeowners face annually. Damage is usually noticed in late July to early August; however, species like black turfgrass ataenius will have two generations per year. Damage from the first generation can occur in late May.

Small or large patches of dead or dying grass will have pruned roots so that sod can be pulled up or rolled back like a loose carpet. Numerous C-shaped, whitish larvae with brown heads will lay in the upper soil directly below dead sod. When birds and some mammals, such as skunks, dig for grubs, this can cause additional damage.

Adults are scarab beetles, including billbugs, black turfgrass ataenius beetles, green June beetles, Japanese beetles, masked chafers and May/June beetles. White grub species can be identified by the time of year when the grub is present; size of the grub; and raster patterns on the abdomen of the grub.

See rasters

Five steps to effective pest management practices

Rasters

White grub raster location
White grub raster location

Japanese beetle raster
Japanese beetle raster

Typical May/June beetle raster
Typical May/June beetle raster

Typical masked chafer raster
Typical masked chafer raster

Green June beetle raster
Green June beetle raster

Black turfgrass ataenius raster
Black turfgrass ataenius raster

Insecticide names

Trade name
Acephate Pro 75
Common name
acephate
Registrant
TopPro

Trade name
Address T/O
Common name
acephate
Registrant
Dow AgroSciences

Trade name
Astro
Common name
permethrin
Registrant
FMC

Trade name
Award
Common name
fenoxycarb
Registrant
Syngenta

Trade name
Azatin XL
Common name
azadirachtin
Registrant
Olympic

Trade name
Battle GC T & O
Common name
lambda-cyhalothrin
Registrant
Lesco

Trade name
Chipco Choice
Common name
fipronil
Registrant
Bayer Crop Science

Trade name
Chlorpyrifos Pro
Registrant
chlorpyrifos
Common name
TopPro

Trade name
Conserve SC
Common name
spinosad
Registrant
Dow AgroSciences

Trade name
Decathlon 20WP
Common name
cyfluthrin
Registrant
Olympic

Trade name
DeltaGard
Common name
deltamethrin
Registrant
Bayer Crop Science

Trade name
Demand CS
Common name
lambda-cyhalothrin
Registrant
Syngenta

Trade name
Demon TC
Common name
cypermethrin
Registrant
Syngenta

Trade name
Dursban
Common name
chlorpyrifos
Registrant
Dow AgroSciences
Lesco
UHS

Trade name
Mach 2
Common name
halofenozide
Registrant
Dow AgroSciences
Lesco

Trade name
Merit
Common name
imidacloprid
Registrant
Lesco

Trade name
Orthene Turf, Tree and Ornamental
Common name
acephate
Registrant
Valent

Trade name
Scimitar GC
Common name
lambda-cyhalothrin
Registrant
Syngenta

Trade name
Sevin
Common name
carbaryl
Registrant
Bayer Crop Science
Lesco
UHS

Trade name
Talstar
Common name
bifenthrin
Registrant
FMC
Lesco
UHS

Trade name
Turcam
Common name
bendiocarb
Registrant
Bayer Crop Science

Trade name
White Grub/Sod Webworm Insecticide
Common name
trichlorfon
Registrant
Lesco

Note
Before using any insecticide, read and follow directions on the label accompanying that product. Reference to specific trade names in this publication does not imply endorsement by the University of Missouri; discrimination is not intended against similar products.

 

IPM1020 Turfgrass and Insects | University of Missouri Extension

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