- Stink Bugs -


Western Conifer Seed Bugs
(aka “Stink Bugs”)

Leptoglossus occidentalis


Intro to western conifer seed bugs

Western conifer seed bugs, or “stink bugs” as they are commonly known, have recently expanded their geographical presence to include the northern US into Canada. One of the reasons for this is thought to be the rise of interstate commerce. They were first reported in California in 1910 and have been overtaking the country since then. Western conifers become a nuisance in homes and businesses when they enter structures seeking protection from cold weather. When handled, they give off a pungent odor.


Biology and behavior

Adult western conifers measure ¾” long and are yellow to light orange with black patches on the upper side of the abdomen with an orange and black pattern on the under side of the abdomen.
Every year, western conifers produce a single generation. Adults emerge from overwintering in the spring and feed on one-year cones. They lay their eggs on conifers, and the eggs hatch within 10 days. After that, the newly hatched nymphs (young insects) feed on needles and the tissue of cone scales. As they age, the nymphs use their mouthparts to pierce and suck on developing seeds for food. In August, the nymphs reach full development. Adults then continue to feed on seeds until they must find shelter from impending cold weather. They do this in pine bark, dead and dry Douglas firs, in hawk and rodent nests, and in buildings. When they enter buildings in large numbers, people become concerned, especially because of their slightly menacing appearance.


Prevention and treatment

So, if you are plagued with western conifer seed bugs, what can you do? The most important thing is to restrict access to the warm harborages your structure provides. Here are some general guidelines:

  • Replace loose fitting screens, windows and doors
  • Caulk gaps around door frames and window frames
  • Caulk cracks behind chimneys and underneath the wood fascia
  • Screen fireplace chimneys and attic and wall vents

To rid your home or business of bugs that have already made their way inside, a licensed pest control operator can effectively eliminate their presence through spraying.


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