Pest description and crop damage Adult moth is reddish brown, with a wingspread less than 0.5 inch, and irregular light and dark bands on the wings. Larvae are 0.5 inch long, yellowish to greenish, with black spots and a yellow-brown head. Pupae are yellow to brown with a white silken cocoon. The larvae skeletonize and roll leaves. They feed on apple, crabapple, cherry, and hawthorn.
Biology and life history Adult moths overwinter in crevices in the tree. They lay eggs in small bunches on the undersides of leaves. The larvae emerge and feed on the underside of the leaves, then move to the top surface and feed there, often tying the sides together creating a "rolled" effect. There is often more than one caterpillar in the roll, and the leaf ends up skeletonized. After 3 to 4 weeks, they pupate in the rolled leaf. Adults emerge after about 2 weeks to start a new generation. There are at least two generations per year.
Scouting and thresholds Watch for signs of skeletonizing, which from a distance looks like the leaf tips have been burned.
Several applications may be needed during season. Do not apply to bloom.
For more information
Johnson, W.T. and H.H. Lyon (1991), Insects That Feed on Trees and Shrubs, 2nd ed., Cornell University Press (p. 216).
PNW Nursery IPM: Apple-and-thorn skeletonizer (http://oregonstate.edu/dept/nurspest/apple_and_thorn_skeletonizer.htm)