Tent Caterpillars

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Malacosoma sp.

Description

The larvae of several moth and butterfly species are referred to as tent caterpillars. The fully grown larvae of tent caterpillars are up to 50 mm long and the body is sparsely hairy. Four common species of tent caterpillars are Eastern Tent Caterpillar, Western Tent Caterpillar, Forest Tent Caterpillar, and Fall Webworm.

Life Cycle

Most species of tent caterpillars overwinter in the egg stage. The egg masses containing 150 to 400 dark brown to gray eggs are attached to the small twigs of trees and shrubs. The eggs hatch in early spring at the same time as unfolding the leaf buds. Caterpillars are gregarious and construct silken tents which they use as a refuge during the early morning and evening hours. They leave their protective tent and feed during the day. Approximately after six weeks, pupation occurs in silken cocoons which are found on tree trunks, fences, or leaf litter. About two weeks later adult moths emerge and deposit the overwintering eggs. Tent caterpillars have one generation a year.

Damage

Tent caterpillar larvae defoliate broad-leaf trees and shrubs in a short time. Trees weaken by repeated defoliation and can be more vulnerable to various stresses, such as drought or infestation by other insects. Besides defoliation, the larvae produce large webs, or tents, in the crotches of tree branches that are a nuisance. Moreover, the immigration of larvae to protected areas to pupate can be a nuisance because thousands of them travel over roads, streets, driveways, walkways, fences, and buildings.

Control

  • V9 Tree Belt

Advice

  • Scrape off and discard overwintering egg masses from branches and twigs
  • Hand-pick caterpillars off leaves and discard them

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