Pseudohylesinus tsugae

Swaine, J.M., 1917

Pseudohylesinus tsugae is a in the , to western North America. It has a with two and four larval , as a fourth-instar . The is closely associated with western hemlock (Tsuga heterophylla), where females feed on the inner bark of living trees before breeding in fresh stumps. It is distinguished from the P. grandis by its preference for stumps over slash as breeding substrate.

Pronunciation

How to pronounce Pseudohylesinus tsugae: //ˌsjuːdoʊhaɪˈliːsɪnəs ˈtsuːɡaɪ//

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Identification

Pseudohylesinus tsugae is distinguished from the closely related P. grandis by its breeding substrate preference: P. tsugae primarily colonizes fresh stumps, while P. grandis prefers fresh slash. Both are with similar , requiring careful examination of use for field identification. The species can be confirmed by association with western hemlock in coastal stands and by its traits, including as a fourth- rather than as a .

Habitat

Young coastal stands of western hemlock (Tsuga heterophylla), particularly in thinned stands where fresh stumps provide breeding substrate. The requires standing live trees for feeding prior to .

Distribution

Western North America. Documented from British Columbia, Canada and Alaska, United States. Distribution corresponds to the range of its tree, western hemlock.

Seasonality

One per year with two . are active during periods when they feed on inner bark of living trees and establish galleries. Overwinters as fourth- .

Diet

Phloem-feeding on western hemlock (Tsuga heterophylla). females feed in the inner-bark region of standing, live trees before initiating .

Host Associations

  • western hemlock - primary Tsuga heterophylla; used for both feeding and larval development

Life Cycle

(one per year) with two and four larval . Overwinters as fourth-instar . females feed on inner bark of standing live trees before initiating galleries in fresh stumps.

Behavior

females exhibit a distinctive pre-reproductive of feeding on the inner bark of standing, live trees before selecting breeding sites. Breeding occurs primarily in fresh stumps rather than slash, a substrate preference that distinguishes this from .

Ecological Role

of dead woody material in western hemlock forests; contributes to through stump in thinned stands. May fungal associates typical of scolytine , though specific fungal relationships are not documented in available sources.

Similar Taxa

  • Pseudohylesinus grandis with similar and ; distinguished by breeding substrate preference (P. grandis uses fresh slash, P. tsugae uses fresh stumps) and stage (P. grandis overwinters as , P. tsugae as fourth- )

More Details

Taxonomic Note

Originally described by J.M. Swaine in 1917. The specific epithet 'tsugae' refers to its association with hemlock (Tsuga). Formerly placed in , now treated as a (Scolytinae) within .

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