Pine Sawfly
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Hosts
Lodgepole and ponderosa pines.
Distribution
Throughout hosts' ranges in Idaho and Montana.
Damage
Larvae can strip all old needles from trees. Now foliage is not eaten. Mortality and top kill can occur on large sawtimber-sized ponderosa pine after 2 years of heavy defoliation.
Identification
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. They are yellow-green with black heads and about five-eighths inch long when fully grown (fig. 136). 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. Female adults are about three-eighths inch long and are yellow-brown. Males are slightly smaller and mostly black.
Similar damages
Defoliation may be similar to that of pine butterfly. Pests are distinctly different, however.
References
Anonymous. 1982. For. Insect & disease identification and management. USDA For. Serv.,Northern Region; Idaho Dept. of Lands, Insect and Disease Control; Montana Dept. of State Lands, Division of Forestry. 192 p.
Furniss, R. L., and V. M. Carolin. 1977. Western For. Insects. USDA Forest Serv., Misc. pub. 1339, 654 p., illus.
Field Guide to Diseases and Insect Pests of Idaho and Montana Forests, USDA Forest Service Northern Region, Publication Number R1-89-54
