University of Maryland Extension

Twig Girdlers and Twig Pruners - Trees

twig girdler damage
Twig girdler (top) and twig pruner damage

Twig Girdler

The twig girdler is a native longhorned beetle that attacks hickory, honeylocust, persimmon, elm, oak, hackberry, poplar, dogwood, linden, and flowering fruits. The adult beetles are about 3⁄4 inch long, cylindrical, and gray with two dark bands across the wing covers. The antennae are longer than the body. The larvae are called roundheaded borers. They are 1 inch long and white with black heads. Female twig girdlers are attracted to individual shade trees. They lay eggs in 1⁄4 to 1⁄2 inch diameter twigs. They then chew (girdle) the twigs, which then drop to the ground (late summer-early fall). The larvae overwinter in the twigs on the ground and complete their development the following summer.

 Management

To monitor for this insect, look for accumulations of twigs under shade trees in August and September. The cut ends look as though they have been cut by a beaver. To control twig girdlers, rake up and destroy twigs in the fall, or the following season before the adults emerge beginning in August. There is no insecticidal control.

Twig Girdler Photos

egg laying twig girdler
Twig girdler laying eggs in twig

white larva
Twig girdler larva

damaged twigs
Twig girdler ends

Twig pruners

Are also native longhorned beetles. They attack oak, hickory, ash, maple, honeylocust, elm, linden, sweetgum, hackberry, and persimmon. The adult beeltes are 3⁄4 inch long, brown, slender, elongate, with 2 posterior spines on each wing cover and have antennae longer than the body. Mature larvae are 1 inch long and white with black heads. Female beetles lay eggs in twigs and branches from 1⁄4 to 2 inches in diameter. The larvae bore toward the trunk and girdle the twigs in late summer. The twigs then drop to the ground. The larvae complete their development, pupate and then overwinter in these twigs.

Management

To monitor for this pest look under shade trees in August and September for accumulations of twigs and small branches that have a concave cut end. Cut the twigs lengthwise to check for mature larvae. Rake up and destroy these twigs in the fall or winter before adults emerge the following spring.

Twig pruner photos

pinned twig pruner
Twig pruner adult

damage to twig
Twig pruner damage

 

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