Pseudohylesinus nebulosus

Swaine, 1918

Douglas-fir pole beetle, Douglas-fir hylesinus

Pseudohylesinus nebulosus is a small bark beetle (2.8 mm long, 1.2 mm wide) native to western North America, ranging from British Columbia to Mexico. It is a slender with strong color markings in dark and light reddish-brown; males are densely clothed with stout and possess a strongly developed epistomal lobe. The species aggregates to trees through primary attraction to host volatiles rather than -mediated secondary attraction.

Bark beetle and wood borer infestation in the Greater Yellowstone Area during four postfire years (1996) (20344959962) by Internet Archive Book Images. Used under a No restrictions license.

Pronunciation

How to pronounce Pseudohylesinus nebulosus: //ˌsjuːdoʊˌhaɪlɪˈsaɪnəs ˌnɛbjʊˈloʊsəs//

These audio files are automatically generated. While they are not always 100% accurate, they are a good starting point.

Identification

Males can be distinguished by dense stout covering the body and a strongly developed epistomal lobe. Females have interspace 9 on the declivity less strongly serrate, with elytral scales that are elongate and become toward the base. The is slender with distinctive dark and light reddish-brown color markings.

Images

Habitat

Found in coniferous forests, specifically associated with the bark of Douglas-fir logs and living trees.

Distribution

Western North America from British Columbia to Mexico; documented from interior and coastal British Columbia, and throughout the Pacific coast region.

Host Associations

Pseudotsuga menziesii - primary preferred
Thuja plicata - western red cedar
Abies grandis - grand fir
Abies amabilis - amabilis fir
Tsuga heterophylla - western hemlock
Pinus ponderosa - western yellow pine

Behavior

Mature males exhibit strong olfactory arrestment to female and stridulate at female galleries. They produce distinct acoustic signals: chirps for stress, attraction, and rivalry, which differ from male vocalizations. Males engage in territorial , pushing intruding males from galleries. Females construct galleries in bark where mating occurs. Reproductively immature males lack aggressive behaviors and show only weak arrestment responses.

Ecological Role

Bark beetle that colonizes weakened or stressed conifers, particularly Douglas-fir.