A bright green lawn with dense turf is the goal of many homeowners. Sometimes, however, insect pests spoil the beauty of lawns. Chinch bugs are a common pest in turf grass throughout subtropical and temperate regions of North America. Their control requires an understanding of their life cycle and the environment they live in.
Chinch bugs, Blissus spp., are black beetles about 3 to 5 mm long with white markings on the wings in an X or chevron pattern. They resemble box elder beetles in their shape and coloration.
When weather warms up in spring, adult chinch bugs lay eggs in sunny, open areas of the lawn. After hatching, the nymphs suck sap from the tender grass blades close to the ground. Nymphs mature in 30 to 90 days, then start a new generation, of which there are typically two or three in a season. Lawns can have chinch bug populations at all stages of development. Adults seek shelter in winter at the base of shrubs and building foundations and emerge in the spring, restarting the life cycle.
Chinch bug damage can be seen in bare patches in open, sunny parts of the lawn. As nymphs kill the grass, they move outward in all directions to to feed on fresh grass. Bare spots are roughly circular.
Confirm the presence of chinch bugs by taking a coffee can with both ends removed and pushing it into the ground at the perimeter of the bare patch. Fill the container with water and wait for the bugs to float to the top. Adults are very active and can often be seen scurrying about the property and bare spot margins in lawns.
The mere presence of chinch bugs in lawns does not require their control. Healthy, dense lawns have the capacity to tolerate some chinch bug damage. Natural predators are present in healthy lawns and usually keep chinch bug populations at a balanced level. Treatment is only necessary in lawns with extensive damage (bare spots).
Insecticides can do damage to beneficial insect populations, so use them only as needed and only in affected areas. Look for turf grass insecticides containing acephate (Orthene), carbaryl (Sevin), cyfluthrin (Tempo) or permethrin (Astro). Use according to label directions.
Keep lawns healthy through proper fertilization, watering and mowing. Over-fertilization encourages thatch, which shelters eggs and nymphs. Water the lawn deeply. Mow no more than one-third the height of the grass and at the recommended height for your species. Avoid the overuse of pesticides in other parts of the garden to encourage a healthy balance of beneficial insects and parasites in the landscape.