Western-hemlock
Guides
Gnathotrichus retusus
western pinewood stainer
Gnathotrichus retusus, commonly known as the western pinewood stainer, is an ambrosia beetle in the family Curculionidae. It is primarily univoltine, with a minimum development time of 40 days from egg to adult in Douglas-fir logs. The species is known to reproduce in both Douglas-fir and western hemlock stumps. Flight activity is strongly crepuscular, with a major peak at dusk and a minor morning peak, regulated primarily by light intensity.
Pseudohylesinus grandis
Pseudohylesinus grandis is a bark beetle (Curculionidae, formerly Scolytidae) associated with western hemlock forests of coastal North America. It completes one generation annually with two broods and four larval instars, overwintering as a teneral adult. The species exhibits distinct breeding habitat preferences, utilizing fresh slash in thinned stands rather than stumps. Adult females engage in pre-oviposition feeding on the inner bark of standing live host trees before constructing egg galleries in slash material.
Pseudohylesinus tsugae
Pseudohylesinus tsugae is a crenulate bark beetle in the family Curculionidae, native to western North America. It has a univoltine life cycle with two broods and four larval instars, overwintering as a fourth-instar larva. The species is closely associated with western hemlock (Tsuga heterophylla), where adult females feed on the inner bark of living trees before breeding in fresh stumps. It is distinguished from the sympatric P. grandis by its preference for stumps over slash as breeding substrate.