Western Conifer Seed Bug

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True Bugs, Pacific Northwest

Western Conifer Seed Bug
Western Conifer Seed Bug, Photo By Bud Logan

The Western Conifer Seed Bug is a pest bug in the Pacific Northwest. This true bug feeds mainly on the seeds and developing cones of several species of conifers and their respective hybrids. This bug has been expanding its range north. Today, its range extends across the northern United States into Canada.

Adults are up to 2 cm long and brownish on top. The upper side of the abdomen is yellow or light orange with five transverse black patches. This orange and black pattern on the abdominal dorsum is revealed during flight.

The flight pattern and loud buzz produced by this strong flying conifer pest resemble those of a bumble bee. The young nymphs are orange and they become reddish brown after a few molts. The eggs, which are laid in chains on conifer needles, measure about 2 mm each in length.
The western conifer seed bug produces a single generation each season. Adults emerge from over wintering sites in late May or early June and feed on one year cones and inflorescence’s.

Eggs laid on host conifers hatch in 10 days, and first instars feed on the needles and tender tissue of cone scales. Later, nymphs use their piercing sucking mouth parts to feed on developing seeds. Nymphs in all five stages of development and new adults can be observed feeding on the same group of cones by mid August, at which time the nymphs begin to reach adulthood.

Adults feed on ripening seeds until early fall and then seek over wintering sites under pine bark, in dead and dry douglas firs, and in eagle and rodent nests. At the onset of cold weather, adult western conifer seed bugs may also enter buildings in search of protected overwintering sites.

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