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Whitemarked tussock moth
Orgyia leucostigma leucostigma (J.E. Smith)

This highly polyphageous insect is native to North America and can be found in Canada from Newfoundland to Alberta. It is considered to be more of a park pest than a forest pest and will feed on most species of hardwoods and many conifers. Larvae appear from mid-April and begin feeding on the leaf surface, eventually consuming the entire leaf (except for the large veins and petiole). They have been known to feed on the twigs which can kill the twig. Despite its wide range of hosts, it is considered to be of minor importance because it is not known to threaten trees. Generally considered a problem on ornamental trees and in plantations, outbreaks of this insect are local and last only a few years.

Points of interest

• one to three generations per year depending on climate; usually one in eastern Canada
• some people develop an allergic reaction on contact with the larvae
• first reported in 1937 in the Maritimes
• average of mature larval or full-grown length is 25–27 mm

References

Martineau, R. 1984. Insects Harmful to Forest Trees. Multiscience Publications Ltd., Montreal, Environment Canada, Canadian Forestry Service, Ottawa, and Supply and Services Canada, Canadian Government Publishing Centre, Ottawa. For. Tech. Rep. 32. 261 p. + x.

Rose, A.H.; Lindquist, O.H. 1994. Insects of Eastern Spruces, Fir and Hemlock. Natural Resources Canada, Canadian Forest Service, Ottawa, and Canada Communication Group—Publishing, Ottawa. Revised edition. 159 p.