Bluegrass billbugLawn Pests
Several insects can attack lawns in Idaho and render them unsightly or unhealthy. Management of these pests can sometimes be problematic because many of the stages are at or below ground making them difficult to monitor. Many times the damage has been done by the time we see the symptoms. Dead or dying patches of lawn that pull up easily are a sign of insect infestation.
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The majority of images in this site are from the Key Gray collection at Oregon State University. The remainder are from the UI slide archives unless noted by individual photos.
| Beetles | Caterpillars | Mites | Flies | Leafhoppers |
Bluegrass billbug
Adults emerge in April and May and can be seen crawling along sidewalks. They are about 10mm long. Adults feed on stems but cause no major damage. Sprays can be applied to kill the adults before they lay adult their eggs.
Billbug larva
Larvae are c-shaped legless grubs that feed in the crowns during May and June and below ground in July and August. July to early August are the times of most damage.
Damaged grass
Damaged grass turns brown and dies. Wilted grass does not respond to watering. Damage oftentimes starts next to sidewalks, driveways, and near trees.
June bug adult
June bug adults feed on fruit trees and other sources. They emerge in May or June and lay eggs during June.
White grub (June bug larva)
White grubs feed on roots below ground for 1-2 years, depending on the species. Grass is killed that is fed on by these larvae and the soil is loose where they have been feeding.
Adult sod webworm moth
These moths can be seen flying in front of the lawnmower or by porch lights at night. They emerge first in late spring or early summer with subsequent generations emerging at 6-8 week intervals.
Sod webworm larva
These caterpillars feed on grass crowns and do not feed beneath the surface. Brown patches will occur where they feed. It takes up to 11 per square foot to make a serious infestation. Lawns treated and watered will rapidly recover from damage by this pest.
Brown patches due to sod webworm
feeding
First signs of damage are leaves that turn yellow or brown during summer. If enough larvae are feeding, brown patches develop.
Red-backed cutworm larva
Cutworms and armyworms feed on grass crowns above ground and sometimes below ground. When they feed below ground you can see pencil sized hole where they come up. They feed mostly at night so are seldom seen. Damage may occur in early spring or later in the summer.
Clover mite
Clover mites occur in lawns that have clover in them. Lawns are not usually damaged by these mites. However, the mites migrate into houses in large numbers and become nuisance pests.
Crane fly adult
Crane flies are generally brownish-red and resemble large mosquitoes. They do not feed on blood. These flies collect on walls of houses and can sometimes be nuisance pests.
Crane fly larva
Larvae of crane flies are sometimes called leatherjackets. They have fleshy protuberances on the posterior end. They feed on grass root, crowns, or leaves but seldom are abundant enough to warrant control efforts.
Green leafhopper
Leafhoppers can become very abundant in Idaho lawns. Control efforts are seldom needed, however. In large numbers they can be a nuisance, however.