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The western conifer seed bug is a nuisance, occasional invader that has been moving eastward from the West Coast. This insect feeds mainly on seeds and developing cones of conifers. It was first detected in Pennsylvania in 1992.  Its range now extends across the northern U.S. and into Canada.  Interstate commerce is the main factor thought to be involved in its spread.

This occasional invading nuisance pest must come inside to overwinter.  That’s when people notice them entering homes and office spaces.  Much like other overwintering pests, the late fall is when they pests will move indoors through cracks and crevices, under eaves and doors, and through weep holes.  And like other occasional invaders, they will rest on the southwest side of the building in late summer months into the fall and work their way toward doors and windows.

The adults are about ¾ of an inch long and brownish on top.  The upper abdomen is orange with five transverse black stripes.  Eggs (2mm) are laid in chains on conifer needles.  Nymphs are reddish brown as they molt from stage to stage and there is one generation per season.  A distinguishing feature of this bug is the larger tibia portion of the leg common to leaf footed bugs.  Another of note is the loud buzzing noise it makes while flying – the sound resembles that of a bumble bee and can be startling to clients.  But, this insect does not bite or sting humans.

To combat their entry you may want to offer to replace loose fitting screens, add door sweeps, caulk any gaps around utility pipe chases, caulk around chimneys and under fascia as well as screen chimneys, attic and wall vents.  Once inside, they will be more active on sunny days and they tend to harbor in voids on cooler or colder days throughout the winter.  When seen on active warmer days, you may recommend that they be vacuumed up and removed.  (The vacuum bag should be frozen first to kill them.)

In the spring they will attempt to get back outdoors to feed and lay their eggs on pineneedles.  They actually do a good bit of economic damage to the quality and viability of conifer seed crops and contribute to a substantial loss of Douglas fir seeds.  It is assumed they will also cause economic damage and impact over time to conifers native throughout the northern U.S. and Canada.