Should I spray the caterpillars on my lawn and sidewalks?

With our mild winter and relatively wet growing season, caterpillars seem to have been eating nearly every kind of plant. With the growing season nearly over, the biggest concern for most homeowners is the health and appearance of the lawn. If you see yellowish-orange caterpillars with long, white hairs crawling across lawns, sidewalks or on the walls of your home, this is the Fall Webworm that has been feeding on trees. These caterpillars are looking for a place to pupate so they can turn into the white adult that overwinters in Oklahoma. If crawling, they are finished feeding. If you see caterpillars that are green and beige striped with few hairs, then you likely have the Fall Armyworm that is now moving into the state from the south. The Fall Armyworm will attack cool season grasses and newly emerging wheat plants. The distinguishing feature of this caterpillar is the upside down ‘Y’ on the front of its head. Young caterpillars eat only the surface covering of grasses, while larger caterpillars will eat the entire blade of plants.

If you decide to try to control caterpillars in the yard, you have many chemical options. Natural products such as B.t. kuristaki or spinosad work best when applying the treatments to caterpillars that are small. They must feed on the B.t. in order for the product to work. There are many synthetic products to choose from with many different brand names. The active ingredient in the products that will control caterpillars are: Acephate, Bifenthrin, Carbaryl, Cyfluthrin, Deltamethrin, Lamda Cyhalothrin, Permethrin and Malathion. Always read the labels on pesticides and follow the instructions.

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If you have questions concerning this topic or related topics, please contact the OSU Extension Center at 273-7683, stop by the office, 14001 Acme Road or visit our website: