Forest Pests: Insects, Diseases & Other Damage Agents

Carpenterworm - Prionoxystus robiniae (Peck)

Solomon, J.D.; Leininger, T.D.; Wilson, A.D.; Anderson, R.L.; Thompson, L.C.; McCracken, F.I. 1993. Ash pests: A guide to major insects, diseases, air pollution injury and chemical injury. Gen. Tech. Rep. SO-96. New Orleans, LA: U.S. Department of Agriculture, Forest Service, Southern Forest Experiment Station. 45 p.

Importance. - Carpenterworms, widely distributed through the United States and southern Canada, bore into trunks and branches. For years, they were recognized mainly as pest of shade, ornamental, and shelterbelt trees, but their impact through log and lumber defects is even more important.

Indentifying the Insect - Young larvae are reddish pink. Mature larvae are creamy white with a shiny, dark-brown head and black mandibles, and are 50 to 75 mm long. Adults are large, grayish moths with black and gray mottled wings; males have an orange spot on their hind wing.

Indentifying the Injury. - The earliest signs of attack are sap spots with fine boring dust. Later, frass is discharged from entrance holes. Larvae chew cavelike burrows 50 mm in diameter and galleries 12 to 22 cm long in the wood. Oval to irregularly shapped bark scars are evident. Damage in sawn lumber appears as pockets of ingrown bark and stained holes 12 mm in diameter.

Biology. - Adult moths appear from April to June and deposit 400 to 800 eggs in bark crevices. Eggs hatch in 10 to 12 days, and young larvae tunnel into the bark and wood. Pupation occurs within the tunnel and lasts 3 weeks. A life cycle requires 1 to 2 years in the South, and 2 to 4 years in the North.

Control. - Open-grown trees are most susceptible, thus stands should be kept well stocked. Brood trees should be identified and removed. Injuries during logging should be prevented or minimized. Natural enemies provide some help. Insecticides can protect ornamental trees.

[ Contents ]     [ Previous ]     [ Next ]     [ Home ]