Eastern tent caterpillar

Malacosoma americanum (Fabr.)

Lepidoptera: Lasiocampidae

Distribution: Most fruit-growing states and provinces in eastern North America.

Photos

Silken tents built between branches by the caterpillars. Marcel Mailloux, Ministry of Ag., Fisheries, and Food
C

The adult is reddish brown with two white, transverse-parallel bands (A). Masses of shiny black eggs are laid in a ring around twigs. Larvae have long silky hairs on their body and a yellow line on their back (B).

Crops Affected: apples, peaches, plums

Damage

Attacks apple, peach and plum. Defoliation of infested branches occurs within a few days. Among the tent caterpillars, only the eastern tent caterpillars build silken tents between the branches of infested trees (C).

Management

Physical control of the colonies by removal of webs and larvae from tree; remove egg masses when detected while pruning. Localized intervention on the most severely infested trees. Economic infestations can be controlled by the use of selective (e.g., Bacillus thuringiensis) or broad-spectrum insecticides.

Similar Species

The forest tent caterpillar (Malacosoma disstria Hübner) adult has brown bands rather than white. The larva has a row of elongated spots. Infestations can be differentiated from those of fall webworm (Hyphantria cunea) by timing (spring, rather than midsummer and later for fall webworm) and location of webbing (in the central crotches, rather than outer regions of branches for fall webworm).