Forest Insects in Canada

This slideshow provides detailed images of some forest insects found in Canada. To capture detailed images of these insects, a digital camera was mounted on a microscope. Individual insect parts were photographed and re-assembled electronically to produce an in focus image of the entire insect.


Forest Tent Caterpillar: This species is a widespread native defoliator of deciduous trees, mainly trembling aspen but also other poplars, willows, birches, and cherries. Outbreaks lasting 2-6 years may occur every 10-15 years, but the trees are seldom killed. Classification: Malacosoma disstria [Lepidoptera: Lasiocampidae]

Asian Long-Horned Beetle: This large beetle from the Far East was first found in the United States in 1996, then in the city of Vaughan, near Toronto, in 2003. It attacks many species of deciduous trees, especially maple, elm and birch. It is the subject of an intense eradication effort that appears to be successful. Classification: Anoplophora glabripennis [Coleoptera: Cerambycidae]

Chalcid wasp: Unintentionally introduced from Asia, this wasp attacks the emerald ash borer. The first North American specimen was found in Virginia in 1994, before the emerald ash borer was even recorded. Only females are known in North America – in Asia both sexes are known – and the population may have been established from a single introduced female. Classification: Balcha indica [Hymenoptera: Eupelmidae]

Smaller European elm bark beetle: This beetle entered Canada in 1948 from the United States, where it was introduced in 1909. It is the principal carrier of the fungus that causes Dutch elm disease, which has almost eliminated large elm trees in eastern North America. It continues to spread in western Canada, east of the Rocky Mountains. Classification: Scolytus multistriatus [Coleoptera: Curcuolionidae, Scolytinae]

Eastern spruce budworm: This is the most destructive native forest insect east of the Rocky Mountains. Seven cyclical outbreaks, each lasting 25-30 years, are thought to have occurred in eastern Canada over the past 250 years. Over 300 000 square kilometres of balsam fir and spruces can be defoliated during a single outbreak. Classification: Choristoneura fumiferana [Lepidoptera: Tortricidae]

Brown spruce longhorn beetle: This species, accidentally introduced from Europe, was first found in 1999 in Point Pleasant Park, Halifax. Although it attacks mainly red spruce trees that are stressed, attacks on healthy trees have been recorded during outbreaks in Europe. Classification: Tetropium fuscum [Coleoptera: Cerambycidae]

Ichneumonid wasp: This widespread native parasitoid has been reared from eastern spruce budworm and several species of moths on deciduous and coniferous trees. It is part of a group of over 20 000 described species of Ichneumonidae, almost none of which have common names. Classification: Patrochloides montanus [Hymenoptera: Ichneumonidae]

Mountain pine beetle: This beetle is the most destructive native insect pest in western North America. Adults carry a blue stain fungus that attacks resin-producing tissues, which reduces the lumber’s value. A beetle epidemic may last 10 years and cover tens of thousands of square kilometres, as in the current outbreak. Classification: Dendroctonus ponderosae [Coleoptera: Curculionidae, Scolytinae]

Chalcid wasp: This species was among the first parasitoids thought to be accidentally introduced from Europe into eastern North America by European settlers and is now transcontinental. It has a wide host range, with 135 different insect hosts reported. In North America only females are known, whereas in the Old World both sexes occur. Classification: Eupelmus vesicularis [Hymenoptera: Eupelmidae]

Emerald ash borer: This beetle, introduced from eastern Asia, was first found in Detroit, Michigan, and Windsor, Ontario, in 2002. It feeds on the inner bark of ash trees and has already killed millions of trees in Michigan, Ohio, Indiana and Ontario. It is under quarantine to slow its spread. Classification: Agrilus planipennis [Coleoptera: Buprestidae]

Gypsy moth: An introduced species first established in Canada in 1924, the gypsy moth is a defoliator of deciduous trees in eastern Canada. British Columbia has experienced isolated infestations of the Asian strain, which was eradicated. The European strain, which is sporadically introduced from eastern Canada, continues to be monitored. Classification: Lymantria dispar [Lepidoptera: Noctuidae, Lymantriinae]

Striped willow leaf beetle: This native leaf beetle feeds on several species of native willows, especially meadow willow, throughout Canada east of the Rocky Mountains. It is not harmful to the forest landscape. Classification: Disonycha alternata [Coleoptera: Chrysomelidae]