Poplar Borer (Saperda calcarata)

From: Ostry, Michael E.; Wilson, Louis F.; McNabb, Harold S., Jr.; Moore, Lincoln M. 1988. A guide to insect, disease, and animal pests of poplars. Agric. Handb. 677. Washington, DC: U.S. Department of Agriculture. 118 p.

Importance- Larvae bore in the stems, roots, and branches of trees 3 years old and older. Several larvae feeding together may riddle the stem, causing the tree to weaken and break. Decay fungi entering through the galleries and woodpecker holes contribute to the tree's death. Attacks are heavier in poorly stocked and thinned stands. Sawtimber from surviving trees is greatly degraded.

Look For: Sap spots and sap mixed with frass oozing from small openings on the mainstem. Split bark at gallery entrances. Coarse, fibrous, frass at gallery entrances, in bark crevices, and at tree base. Yellow-white legless larvae up to 1¼ inches long in galleries in the wood. (Cut stem open to see this.)

Sap streak and frass of poplar borer Photo by Minnesota Department of Natural Resources Archives

Biology- The grayish-blue spotted female beetle lays eggs in late spring and early summer in slits chewed in the bark. Larvae bore into the stems or branches and make extensive galleries in the sapwood and heartwood. After 2 years' growth, the larvae pupate and adults exit through the former entrance hole.

Life stages and injury of poplar borer Photo by James Solomon, USDA Forest Service

Monitoring- Inspect 3-year-old or older trees for signs of boring injury. Sometimes individual trees become brood trees after repeated attacks. Consider treatment when 10 percent of sample trees are attacked.

Control: Remove brood trees and heavily injured trees. Maintain well-stocked stand until harvest. Clearcut at harvest. Apply an insecticide recommended for boring insects to kill adults in spring.

"Sap streak from poplar borer feeding.

For Additional Information:

Ewan, H.G. 1960. The poplar borer in relation to aspen stocking. Tech. Note 580. St. Paul, MN: U.S. Department of Agriculture, Forest Service, Lake States Forest Experiment Station. 2 p.

U.S. Department of Agriculture, Forest Service. 1985. Insects of eastern forests. Misc. Publ. 1426. Washington, DC: U.S. Department of Agriculture, Forest Service. 608 p.