Carpenterworm
Prionoxystus robiniae |
| USDA Forest Service. 1979. A guide to common insects and diseases of forest trees in the northeastern United States. Northeast. Area State Priv. For., For. Insect and Disease Management., Broomall, PA. p. 123, illus. |
This hardwood borer damages millions of dollars worth of sawtimber each year. Species in the red oak group are most heavily damaged, but additional hosts include black locust, cottonwood, elm, maple, and willow.
The mottled gray-black adult moths appear in late May or early June. Males have an orange spot on each hindwing; females are considerably larger than males, with an average wingspan of 3 inches. Soon after mating, females lay about 500 eggs in groups within bark crevices, inside cracks, under lichens, or in other secluded areas. Upon hatching, larvae move about on the bark surface searching for a suitable feeding site. Larvae range in color from pinkish orange to greenish white. When full grown, they average 2½ inches in length. The larvae gradually bore into the sapwood and heartwood, usually producing a sap stain on the outer bark. After a larval period of 2 to 4 years, the insects pupate deep within the heartwood and emerge as adults through large exit holes.
Damage; feeding laterally across trunk (note frass covering gallery)
Photo by James Solomon, USDA Forest Service |
Adult(s); male (right) and female (left) moth
Photo by James Solomon, USDA Forest Service |
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