Pine (Pinus)-Pine sawfly

Includes Neodiprion nanulus contortae

Pest description and damage Larvae are yellow-green with black heads and about 0.63 inch long when fully grown. Female adults are about 0.38 inch long and are yellow-brown. Males are slightly smaller and mostly black. Larvae can strip all old needles from trees. New foliage is not eaten. Mortality and top kill can occur on large ponderosa pines after 2 years of heavy defoliation. Defoliation may be similar to that of pine butterfly. Larvae and adults are distinctly different, however.

Biology and life history Pine sawfly overwinters as eggs inside slits in pine needles. Eggs hatch from late May to early June and larvae feed gregariously on old foliage into July. Last instars drop to the ground and pupate in papery, tough cocoons in the duff. Adults emerge from late September to late October and lay eggs in niches cut in needles.

Management-biological control

Sawflies are subject to various viral and fungal diseases. Rodents and birds are important predators, but outbreaks can still occur.

Management-chemical control

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