Southern Clearwing Moth (Paranthrene tabaniformis)

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 attack the terminal shoot of young Populus. Weakened terminals may break over, causing malformed or bushy trees. Borer holes are infection courts for pathogens.

Look For: Sap flow from stem about 12 to 36 inches below the tree tip. Swollen stem or broken over terminal. White to pinkish larvae with brown heads about 1 to 1½ inches long inside stem below terminal.

Gallery and larva of clearwing borer Photo by James Solomon, USDA Forest Service

Biology- Adult females lay eggs in the bark crevices on the upper stem. Larvae hatch and tunnel in the main stem. Larvae overwinter in the galleries and pupate in the spring. Adults emerge in April in the first generations. Second-generation adults emerge in August.

Woodpeckers often reduce populations of larvae, but they may aggravate the damage by making the shoots more attractive to the moth and adding additional sites for fungi.

Monitoring- Inspect nurseries and young plantings for evidence of the borers. If you find a light infestation, re-examine in next 2 years to determine population status. If 5 percent of the trees show damage in the nursery or 20 percent in plantings, consider treatment.

Control: Cut and destroy all infested material in nurseries. Plant uninfested cuttings. Apply an insecticide recommended for wood-boring insects.

Clearwing borer entrance hole.