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This solitary defoliator, native to North America, has a range that coincides almost exactly with jack pine, its preferred host. In Canada, you will find this insect from New Brunswick to Alberta. It can also be found on Scots pine and occasionally on fir and larch where these are associated with jack pine. In mixed stands, damage to white and red pine can also occur. Foresters are particularly concerned with this pest due to the significant damage caused in natural jack pine stands and Scots pine plantations. Damage from this insect is due solely to the larvae and repeated attacks may lead to tree mortality. Often only the upper crown is destroyed resulting in trees that are deformed, and growth reduction is common. Trees may require many years to recover. Outbreaks typically last 2–3 years with a recurrence every 6–8 years.

Points of interest

• long believed to be the eastern spruce budworm, only in 1953 was it recognized as a distinct species
• most damage occurred in Ontario, Manitoba, and Saskatchewan
• larvae are wasteful feeders—they cut the needle at the base and eat only the base portion, leaving the rest of the needle tangled in silk
• this waste eventually turns reddish brown, the dominant color in an infested stand

View the distribution map (1980–1995)

Ives, W.H.G.; Wong, H.R. 1988. Tree and shrub insects of the prairie provinces. Can. For. Serv., North. For. Cent., Edmonton, Alberta. Inf. Rep. NOR-X-292. 327 p. + xii.

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.; Nystrom, K.L. 1999. Insects of Eastern Pines. Natural Resources Canada, Canadian Forest Service, Ottawa. Revised edition. Publ. 1313. 128 p.