Includes Neodiprion nanulus
Pest description and damage Larvae are yellow-green with black heads and about 0.63 inch in length when fully grown. Female adults are about 0.38 inch in length 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 two 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.
Sawflies are subject to various viral and fungal diseases. Rodents and birds are important predators, but outbreaks can still occur.
See Table 2 in:
Chemical Control of Landscape Pests
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