When at rest, the wings are held roof-like over the body. Newly hatched larvae are whitish to pinkish in color.
Older larvae are olive gray then jade green, with yellowish-brown heads.
Mature larvae are about 12 to 13 mm long. In the spring, young overwintering larvae feed on developing buds and then bore into young tender shoots. Newly hatched first generation larvae feed on buds and newly set nuts. Infested nuts are held together by a cluster of silken threads. They are easily recognized by the frass cast out by the larvae.