Monochamus spp. (Cerambycidae)

sawyer beetles


Monochamus scutellatus, the sawyer beetle, adult male.

Monochamus scutellatus, the sawyer beetle, adult female.
Family characteristics of antennae, eyes and tarsi + generic characteristics of elongate cylindroidal form, prothorax with small conical projections from side, antennae very long, second segment very small.


Cerambycid grub Elongate slightly tapered grub with thoracic plate above but none below, elliptical in cross-section, legs absent.


Grubholes elliptical, frass-filled, adult exit holes circular. Initial stage of attack shows as irregular channelling of wood surface. Larvae may tunnel more than one year before pupation.

Principal Hosts:

Species of Pinus, Picea, Abies and Douglas-fir.

Economic Importance:

Larval boring causes extensive damage to dying, recently dead and felled conifers.

Monochamus spp. are also the vectors for Bursaphelenchus xylophilus, the Pinewood Nematode. This nematode pathogen feeds on blue stain fungi innoculated into a weakened tree, but can also kill susceptible healthy pine trees by clogging vascular bundles, causing a condition called pine wilt disease.

In China and Japan, pine wilt disease, vectored by M. alternatus, is a serious threat to forestry.

References and Links:

EAG: 532; FC: 309-311.

Additional Images of other Monochamus spp.:

M. clamator female M. clamator male M. obtasus female and male