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PINE SAWYERS (Coleoptera: Cerambycidae, Monochamus sp.)

Authors as Published

Eric Day, entomologist, Virginia Tech


figure 1 Fig. 1: Pine Sawyer adult on branch [W Cranshaw, Colorado State University, Bugwood.org]

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 larvae are elongate, cylindrical, and have large gnawing mandibles. 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.


figure 2 Fig. 2: Pine Sawyer larvae [J Song and J Shi, Beijing Forestry University, Bugwood.org]


Figure 3 Fig. 3: U-shaped cells in wood [W H Bennett, USDA Forest Service, Bugwood.org]

CONTROL: Sanitation and prompt actions are the best controls against these borers. Felled timber should be removed from the woods as soon as possible. Secondly, the bark should be removed from the logs to prevent infestation. 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 emerging from homes.


Virginia Cooperative Extension materials are available for public use, re-print, or citation without further permission, provided the use includes credit to the author and to Virginia Cooperative Extension, Virginia Tech, and Virginia State University.


Issued in furtherance of Cooperative Extension work, Virginia Polytechnic Institute and State University, Virginia State University, and the U.S. Department of Agriculture cooperating. Edwin J. Jones, Director, Virginia Cooperative Extension, Virginia Tech, Blacksburg; Jewel E. Hairston, Administrator, 1890 Extension Program, Virginia State, Petersburg.


August 5, 2009

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