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Moderate to large size (13-27 mm) with shinny black integument. Relatively hairless, but if hair present usually brownish. Antennae extending 6 segments or more beyond elytra in males and only 2-3 segments beyond the elytra in females. Lateral projections of pronotum large and blunt. Scutellum covered in white hairs. Females are larger than males (not including antennae) and elytra covered in patches of white hair. The subspecies Monochamus s. scutellatus is characterized by metallic looking integument and reddish legs. The other subspecies, Monochamus s. oregonensis, is distinguished by lacking metallic looking integument, females with white patches on antennae and lacking hairs on elytra, and legs black. (Linsley and Chemsak, 1984; Yanega, 1996). Royal Alberta Museum page

The life cycle can take 1 to 2 years to complete, but usually 2 in the more colder areas. Adults emerge around April to June. They will then feed on coniferous foliage and bark until mating occurs. Females will deposit eggs into slits they have chewed into the bark. The larvae will emerge in around 2 weeks and begin feeding. The larvae will overwinter and then make their back to the surface, creating a u-shaped excavation tunnel. They will then pupate near the surface and adults will emerge next spring. (Ives and Wong, 1988; Raske, 1972). Monochamus scutellatus can cause serious defoliation around large clear cut areas (Ives and Wong, 1988).

Monochamus s. scutellatus can be found from Alaska to Newfoundland and as southernly as Arizona. Monochamus s. oregonensis is located from British Columbia to California (Bousquet, 1991; Linsley and Chemsak, 1984).