Insecticide Treatments Forest tent caterpillar rarely causes severe damage to trees and, as a result, the forest does not normally need the protection of pesticides. Natural control systems cause the collapse of populations resulting in cyclical outbreaks. Private landowners may desire or justify spraying in order to protect the leaves and preserve aesthetics. In making this decision the landowners should consider their goals, environmental concerns and their ability to pay. The DNR provides technical advice to landowners and landowner groups wanting to undertake control programs.
Advice includes evaluation of alternatives, pesticide selection, spray timing, and contracting.
When applied while the caterpillars are small, insecticides can protect the foliage and the aesthetics of an area. Several insecticides are registered for controlling the forest tent caterpillar. The DNR strongly recommends the use of Bt because of its environmental safety. Bt is a naturally occurring bacteria effective against caterpillars and is registered as an insecticide by several companies. It has no effect on most insects, birds, people, and other animals.