Many insects and insect-like pests damage lawns and other turf. They cause the grass to turn brown and die, or they build unsightly mounds that may smother the grass. Some pests infest the soil and attack the plant roots, some feed on the plants' leaves and stems, while others suck juice from the plants. Other insects and insect-like pests inhabit lawns, but do not damage them. The pests are annoying and some of them attack
people. These pests can be controlled with insecticides and other methods.
Pests That Infect Soil and Roots
White Grubs
White grubs are the larvae of several species of beetles. They are whitish or grayish, have brownish heads and brownish or blackish hind parts and are usually found in a curled position when disturbed. They hatch from eggs laid in the ground by the female beetles. Most of them spend about 10 months in the ground; some remain in the soil two or three years. In mild weather, they live 1 to 3 inches below the surface of the lawn; in
winter, they go deeper into the soil. They burrow around the roots of the grass, then feed on them about an inch below the surface of the soil. Moles, skunks and birds feed on the grubs and may tear up the sod in searching for
them. You can estimate the grub population of your lawn. Do this in early to mid- August or in the spring after the soil warms up and the grubs are near the surface. With a spade, cut three sides of a strip 1-foot square by 2 or 3 inches deep. Force the spade under the sod and lay it back, using the uncut side as a hinge. Use a trowel to dislodge soil on the overturned roots that might contain grubs. Count the grubs in the exposed soil. Replace the strips of sod. In the same way, cut strips of sod in several other parts of the lawn, and count the grubs under each strip. To calculate the average number of grubs per square foot of lawn, divide the total number of grubs counted by the number of strips. The average number of grubs per square foot is a measurement of grub density. Economic thresholds based on grub density is a personal decision.
Insect Control. The parent beetles differ in appearance, distribution and habits. The following are important in lawns:
May Beetles. -
These beetles are brown or blackish-brown.
More than 200 kinds are found in the United States. Sometimes
they are called June beetles. The adults of the species emerge in
the early spring. Most species begin emerging in May or June
and can be active throughout much of the summer. Eggs laid in
July and early August soon hatch into young, which are called
white grubs. Some of them remain in the soil two or three years and may feed on the grass roots during several seasons.
Japanese Beetle
- The beetle is about1/2 inch long and has a shiny metallic-green body; it has coppery brown wing covers and six small patches of white hair along each side and the back of the body, just under the edges of the wings.
The adult insect feeds on many different plants. These insects are found mostly in the Eastern States. The
adult beetles begin to appear in late May and are active for four
to six weeks. The young are sometimes called annual white grubs because the life cycle of the insect is completed in one year.
Asiatic Garden Beetle
- The beetle is about 1/4 inch long, is
chestnut brown and has a velvety appearance. The underside of
the body is covered with short yellow hairs. The insect flies only
at night and feeds on various kinds of foliage. They are most
abundant from mid-July to mid-August. They complete their life
cycle in one year.
Oriental Beetle
- The beetle is about 5/8 inch long, is strawcolored
and has some dark markings on the body. The beetles
have been recently detected in East Tennessee. At present, the
distribution of this pest in Tennessee in uncertain. They appear in
late June and July. Grubs prefer unshaded lawn and short grass.
Masked Chafers
- These beetles are 1/2 inch long and
brown. They live in the soil during the day and emerge at night; they are especially active on warm humid evenings. The northern masked chafer
is found from Connecticut south to Alabama and west to California. In Tennessee, the distribution of the northern masked chafer overlaps southern masked chafer, which is common in the Southeastern states. asked chafers appear in late May, June and July and are active one or two months. These annual white grubs have
irregularly arranged spines on the underside of the last body segment (raster).
Rose Chafer - The beetle is 1/2 inch long and is yellowish brown; it has long spiny legs. Rose chafers feed on almost any vegetation and are very destructive to roses in bloom. They prefer areas in which the soil is light and sandy. They are abundant in June and early July. The grubs are not so harmful to lawns as some of those mentioned above.
Green June Beetle
- The beetle is nearly 1 inch long. The body is nearly flattened; it is velvety green and has bronze to
yellow edges. The insects feed on the foliage of many trees and
plants. The females often lay eggs in piles of grass clippings,
mulched plant beds and in the soil. They are active in June, July
and August. They produce one generation a year.
The grubs feed mainly on decaying vegetable matter. Their
burrowing tends to disturb grass roots by separating them from
the soil, causing the grass to dry out and die. The grubs can be especially damaging in newly sown lawns. Damage is most severe in dry seasons and is most apparent in the fall. Sometimes after a heavy rain or during warm nights with heavy dew, the grubs come out of the soil and crawl on the surface of the ground. They have the unusual habit of crawling on their backs.
Ants
Ants build nests in the ground. Some ants form hills around
the openings of their nests; fire ants can build large mounds. The
anthills and mounds often smother the surrounding grass. If the
ants nest about the roots of the grass, they may destroy them.
Ants also destroy grass seeds in the ground and prevent good
stands. Ants like to feed on the a substance secreted by clover called
Honeydew, and will spread the clover as well as choke out the grass.
Some ants bite or sting people and animals. Imported fire ants and harvester ants are especially vicious.
Mole crickets are light brown, with a lower surface lighter than the upper and often tinged with green. They are about 1-1/2 inches long and have short, stout forelegs, shovel-like feet, and large, beady eyes. Mole crickets feed on the roots of the grass. In addition, their burrowing uproots seedlings and causes the soil to dry out quickly. The type of mole cricket found in most common in the U.S. is called the Northern mole cricket. It is not as damaging as some of the species found in coastal states. It can be a pest, especially in golf
course greens.
Wireworm
1-1/2 inches long and are usually hard, dark brown, smooth and
slender. Some wireworms are soft and white or yellowish.
Wireworms bore into the underground part of the stems and feed
on the roots of the grass. The boring causes the plant to wither
and die.
The adults are about an inch long, and brownish, grayish or
nearly black. They are hard-shelled and their bodies taper
somewhat at each end. When they fall on their backs, the beetles
flip the middle part of the body against the ground, throw
themselves several inches into the air and make a clicking sound.
Cicada-Killer Wasp
the cicada. These wasps, which appear in late July and August, cause damage to lawns by their burrowing. While they fly around aggressively, they usually do not sting people unless they are provoked.
Wild Bees
Some kinds of wild bees occasionally damage lawns by digging up the soil, making holes and forming mounds thatinterfere with the growth of grass.
Periodical Cicada
to appear in your region, the holes in your lawn were probably made by the emerging nymphs. If a large brood is emerging.
Billbugs
The young, or grubs, are small and white, and have hard brown or yellow heads. They feed on the roots of grass.
Adult billbugs are beetles 1/5 to 3/4 inch long. They have
long snouts, or bills that carry at the tip a pair of strong jaws or
mandibles with which the beetles chew their food. Their color is
clay yellow to reddish brown to jet black. The beetles burrow in
the grass stems near the surface of the soil and also feed on the
leaves.
Several species of billbugs damage lawns. The bluegrass
billbug is a pest of Kentucky bluegrass, while the hunting billbug
causes damage to Zoysia grass.
Earthworms
When earthworms are numerous, they sometimes become
pests in lawns. They make small mounds of castings that ruin the
appearance of the grass.
An imported species, the oriental earthworm, is found in
some of the eastern United States. It is 6 to 8 inches long and
about 1/5 inch in diameter. It is light green on the upper surface
and has purplish-green line down the center of the back. It
throws up abundant castings of soil.
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