Chinch Bugs

- Damage turf and grains in dry years -

Summary: Chinch bugs are small bugs that feed on the leaves of grasses and small grains. Damage is greatest during dry summer months. Turf grass can often survive if properly fertilized and irrigated but there are several treatment options as well.

Jack DeAngelis, PhD

OSU Ext. Entomologist (ret.)

Chinch bug identification

Chinch bugs (see drawing right and color picture here) are small, true bugs (Hemiptera) that damage turf grasses and grain crops such as wheat and sorghum. There are a number of different species. Immature chinch bugs look like small, wingless adults and feed on the same plants.

Chinch bugs cause irregular patches of dead or yellowed turf and are especially damaging during hot, dry summers following a dry spring. Some regions are plagued by chinch bugs year after year while others only occasionally see this pest. There are 2-6 generations per year depending on climate. Damage is most severe when chinch bugs are not detected early in the season and bug populations are allowed to build to high numbers.

Since early chinch bug detection is so important in order to prevent turf damage you should scout for chinch bugs if (1) you live where these bugs are normally a pest (check with local Extension or lawn care experts) and (2) if you experienced a dry spring and early hot summer.

common names: southern chinch bug, hairy chinch bug

chinch bug (drawing) ~ 1/8" long

Scouting for chinch bug:

Method 1: With your hand lens or magnifying glass carefully inspect grass blades especially near the soil surface. Look for chinch bugs and damage. This inspection will give you a rough idea of the of the population size but it can be tedious especially if the infestations are spotty or the area to be scouted is large.

Method 2: Make a tube out of plastic pipe, 4" diameter or larger, or a large metal canned food-type can with the bottom removed. Twist one end into the soil. Fill the tube with water or a 1% soap solution. Chinch bugs will float to the surface after a few minutes where they can be counted. Greater than 20 chinch bugs per square foot (convert the area of the can opening to square feet) probably warrants control. Repeat this inspection at least several times in random locations in the area to be scouted.

How can I avoid damage from chinch bugs?

Healthy grass will resist most injury. Watering and light fertilizer applications seem to suppress chinch bug populations. However, if you detect significant chinch bug numbers, especially early in the summer following a dry spring, chemical control may be needed.

Insecticidal soap (see Using Insecticidal Soap) is an excellent, low toxicity spray for chinch bugs. You can spot spray infested areas with a garden sprayer. Follow label instructions carefully. While soap is effective and safe it is difficult to spray large areas like a lawn.

Granular insecticides such as imidacloprid (Bayer Advanced, see Merit Insecticide), bifenthrin (Talstar EZ) or deltamethrin (Deltagard G) will be easier to apply to large areas because they can be applied using an ordinary fertilizer spreader. Conventional insecticides are considerably more hazardous than soap, however.

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