Western Conifer Seed Bug: Q & A

By Chris Williams on October 13, 2010.

Q. We’ve seen a number of these large brownish insects on the side of our house and I’ve found a couple of them inside. They look kind of scary; do they bite?

western-conifer-seed-bugA. You’re probably talking about the western conifer seed bug. It’s a seasonal pest in our area in the fall when it tries to move into buildings to spend the winter. Once inside, seed bugs will usually find a hidden, protected place such as inside wall voids or in the attic. And no, they will not bite or sting, or reproduce inside, or damage anything in your home. They are mostly a temporary annoyance. On warm days in the winter, they can become active inside. They usually do not survive the winter in the drier air inside homes.

As you might guess from its name, the western conifer seed bug was found originally in the western United States. It has been slowly extending its range eastward and is now an established pest in certain areas of the northeastern U.S.

During warm weather months, the seed bug is outside feeding on the seeds and cones of conifer trees. It belongs to an insect family called the “leaf-footed bugs” because its lower back legs have a flattened leaf-shaped expansion. These 3/4-inch long seed bugs can fly and when they do they buzz like bumble bees, exposing orange and black stripes on their abdomen. They congregate on outside walls (especially those facing south), and around doors and windows looking for a way to get inside.

Like Asian lady beetles and most other fall invading insects, western conifer seed bugs are tough to control once they are inside and hidden. Keeping them from entering in the first place is the best way to control these bugs:

  • Replace loose fitting screens and caulk any gaps around window and door frames
  • Install sweeps or thresholds under doors
  • Caulk any gaps around soffits, underneath wood fascia, and around chimneys
  • Make sure that attic and wall vents and fireplace chimneys are screened
  • Store firewood outside and away from the house

If they do get inside despite your best efforts, reach for the vacuum. The seed bugs can give off a defensive odor when disturbed but most describe it as sort of a “piney” scent. Could be worse!



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