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Forest Tent Caterpillar

This forest tent caterpillar is almost ready
to pupate into a moth

The forest tent caterpillar (Malacosoma disstria) is a native insect common across the prairie provinces. The caterpillars hatch from eggs into their larval stage in late May. 


Forest tent caterpillars are about 5cm long, and black/dark brown/grey in colour with blue and faint yellow longitudinal stripes. The caterpillars have long setae, giving them a furry look.

Plants Affected


Forest tent caterpillars can defoliate branches or even whole trees if populations are high.

Outbreak populations occur approximately every ten years but any region may not experience an outbreak if late frosts or disease increase mortality.


On smaller trees control may be achieved by hand picking the caterpillars as they cluster on the trunk/branches early in the morning. Healthy trees seldom die from infestations of tent caterpillars.

Where trees are too large for hand picking of caterpillars, or for trees under heavy infestation, a properly timed application of a Btk insecticide (Bacillus thuringiensis var. kurstaki) should prevent branch defoliation.


Forest Tent Caterpillars

Forest Tent Caterpillar Cocoon
Forest Tent Moth and Egg Band

 Forest tent caterpillars are vulnerable to mechanical control (picking & squishing) at every stage of growth,
from egg band to larvae to cocoon to adult.


Last updated: 2/27/2017 1:38:44 PM