How to Manage Pests
UC Pest Management Guidelines
Forest Tent Caterpillar
Scientific names: Malacosoma disstria
(Reviewed 3/09, updated 3/09)
In this Guideline:
DESCRIPTION OF THE PEST
The forest tent caterpillar overwinters in the egg stage, and eggs give rise to destructive caterpillars in spring and early summer. The caterpillars are grayish with yellow stripes along the side, separated by a broad blue stripe. There is a row of white, keyhole-shaped spots on the back. There is one generation each year.
Defoliation caused by tent caterpillars may be serious on individual trees and along orchard edges, but is usually randomly scattered throughout the orchard. Young orchards are usually the most severely affected. From April to June, caterpillars feed on leaves; young caterpillars skeletonize the leaves, whereas older caterpillars consume the leaf, leaving only the midvein.
On small trees, infested twigs may be cut out and destroyed. Spray programs for other insects generally reduce populations. If insecticide treatments are required, localized treatments on individual trees and branches are generally all that is necessary. Treat when small caterpillars are first observed. Populations usually decline naturally due to disease.
UC IPM Pest Management Guidelines:
Insects and Mites
F. G. Zalom, Entomology, UC Davis