Poplar Root Girdler (Agrilus horni)

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-  The larvae girdle stems by feeding particularly in sparsely stocked stands in northeastern North America. Young trees usually die from only a few larval attacks.

Look For: Dead or dying trees. Larval galleries at the tree base that appear as swollen areas encircling and forming a helix around the stem. Irregular larval galleries with tightly packed excrement on the wood surface. (Remove bark to see these.)

Poplar root girdle injury Photo by James Solomon, USDA Forest Service

Biology- After the female beetle lays eggs in the bark at the base of the tree in spring, the emerging larval tunnel into the stem and roots and feed in the cambium. The life cycle lasts 2 years.

Galleries made by poplar root girdler Photo by James Solomon, USDA Forest Service

Monitoring- Inspect young trees (2 to 6 inches in diameter) for signs of injury. An occasional infected tree is usually not a cause for concern. If 10 percent of the trees become infested, treat the stand.

Control:

• Maintain healthy trees and full stocking.
• Cut and destroy infested trees.
• Apply an insecticide recommended for wood-boring insects to the base of the tree to control adults.