Leptoglossus occidentalis is a member of the family Coreidae, the leaf-footed bugs. As such, it has the characteristic swellings of the hind tibia. The adults average between 1.5 - 2.0 cm. in length and approximately 0.5 - 0.7 cm in width. Most of their body varies in colour from a reddish brown to a grey brown. L. occidentalis can be readily distinguished from other species of similar Coreidae by the diagnostic white wavy line across the hemelytra (forewings), and by the five dark patches down each side of the abdomen, as shown in the diagram.

There is one generation per year of this insect with late stage nymphs and adults overwintering. In the spring, the females lay rows of four or five eggs on the needles of Douglas Fir and several species of pines. These eggs hatch in approximately 10 days. Both the nymphs and the adults feed on the seeds of the pines (not the foliage) throughout the summer. At the onset of cold weather in the fall, the adults and nymphs begin to look for a place to over winter and burrow down into the leaf litter on the forest floor or in a crotch of a tree, or sometimes enter buildings. The bug has been expanding its range eastward from its natural habitat on the west coast of north America. It has been found in Ontario since about 1985. On the west coast, it is known to feed on Douglas fir and ponderosa pine, and can be a pest of conifer seed orchards. In the east, it is thought to feed on red pine and Scots pine.

In Ontario, L. occidentalis is not known to be a pest until it starts showing up in houses in September and October. Since it must feed on the seeds in the cones of certain coniferous trees, it cannot breed in houses and is not known to be harmful to people. In houses no chemical control is necessary. Simple removal of the insect from the house as well as ensuring doors and windows are properly screened and sealed, to prevent entry, should eliminate the problem.

J. Swann

PDCF-070 (Revised 2033/01/04)