Coleoptera: Cerambycidae, Monochamus sp.
by Eric Day
PLANTS ATTACKED: Pine, spruce, and balsam fir.
DESCRIPTION OF DAMAGE: They are secondary infesters whose
main damage is disfiguring wood by larval boring and tunneling in
felled trees and usable trees which are weakened or dying from other
causes. Plant parts attacked trunk. Damaging stage - larvae.
IDENTIFICATION: The adults are large cylindrical beetles, black,
brownish-black, or reddish brown, mottled with whitish or grayish
pubescence. The thorax bears a prominent spine on each side. The
Fig. 1: Pine Sawyer adult on branch larvae are elongate, cylindrical, and have large gnawing mandibles.
[W Cranshaw, Colorado State University, The larvae are legless.
LIFE HISTORY: Adult appearance coincides with the pollen release by the host plants.
Shortly thereafter they begin attacking killed and felled trees, gnawing pits through the
bark, and inserting from 1 to several eggs in each pit. Upon hatching, the larvae bore
beneath the bark and mature between 40-60 days. At this time the larvae enter the
wood and make a deep U-shaped cell through the sap and heartwood. The entrance is
plugged with frass, and the opposite end enlarged into a pupal cell. The larvae pupates
the following spring or early summer and the adult emerges the same summer.
CONTROL: Sanitation and prompt actions are
the best controls against these borers. Felled Fig. 2: Pine Sawyer larvae
timber should be removed from the woods as [J Song and J Shi, Beijing
soon as possible. Secondly, the bark should be Forestry University,
removed from the logs to prevent infestation. Bugwood.org]
Thirdly, logs may be sprayed thoroughly if storing is required.
REMARKS: Adults are attracted to the smell of various materials with
resin bases; turpentine, paints, etc., and are occasionally thought to be
Fig. 3: U-shaped cells in wood emerging from homes.
[W H Bennett, USDA Forest Service,
Formerly Publication 444-215
2009 Virginia Polytechnic Institute and State University 2907-1399
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An equal opportunity/affirmative action employer. Issued in furtherance of Cooperative Extension work, Virginia Polytechnic Institute and State University, Virginia State University, and the U.S. Department
of Agriculture cooperating. Mark A. McCann, Director, Virginia Cooperative Extension, Virginia Tech, Blacksburg; Alma C. Hobbs, Administrator, 1890 Extension Program, Virginia State, Petersburg.