Tent Caterpillars

Characteristics

Tent Caterpillars feed on the leaves of various trees and shrubs. Some of their favourite trees to feed on are fruit trees, ash, birch, willow, witch-hazel, maple, oak, poplar. Outbreaks can last two or more years and usually happen at intervals of ten years or more. There is only one generation of caterpillars per growing season.

Eastern Tent caterpillars are hairy, brownish-black, and have a light stripe down their back. These caterpillars pupate into reddish-brown, or yellow-brown moths.

Forest Tent Caterpillars are pale blue-black, and have a series of white spots on their back. Forest tent caterpillars pupate into yellow-brown moths.

Tent caterpillar moths lay their eggs in late June-July. The eggs remain on the trees until spring when they hatch. The young caterpillars will gather at branch unions to build a nest. From there they will feed on the newly opened leaves. Caterpillars will feed on the foliage of trees and shrubs, and multiple years of defoliation can cause unnecessary stress. Stressed trees are more prone to insect and disease problems.

Signs & Symptoms

Egg masses will be visible on the tree, as well as the silk trails that are left behind as the caterpillar moves. White silk nests will be visible in the branch unions. Leaves may be defoliated from feeding caterpillars.

Treatment

Egg masses can be removed during the winter, and nests can be removed on rainy, cool days. Caterpillars will not venture out of their nest to feed during inclement weather. Regular intervals of fertilizer will provide improve tree and shrub vigor. Trees with good vigor are less of a target for tent caterpillars.

A dormant oil application in early spring can help to control the population. Severe infestations may require additional treatment.

For more information on tent caterpillars talk with one of our qualified arborists.