European pine sawfly (Neodiprion sertifer)

From Bugwoodwiki

U.S. Department of Agriculture, Forest Service. 1979. A guide to common insects and diseases of forest trees in the northeastern United States. Northeast. Area State and Private Forestry, Forest Insect and Disease Management., Broomall, PA. p. 123, illus.(USDA Forest Service, Northeast Area State and Private Forestry Publication. NA-FR-4)

The European pine sawfly prefers the old foliage of Scots, red, jack, Japanese red, Table-Mountain, and mugho pines, although other pines may be defoliated when growing in mixture with these preferred species. The sawfly may also feed on tender bark, causing branch or terminal shoot deformation and occasional branch mortality. Trees of all sizes are defoliated, causing growth reduction but rarely tree mortality.

This sawfly overwinters in the egg stage; larvae emerge in mid-April to early May and begin feeding in colonies. Mature larvae have black heads and gray-green bodies with several stripes or rows of spots of varying shades of green. They pupate in cocoons in the duff or in protected places on the tree. Adults emerge in the fall and deposit eggs in slits in the needles. Eggs are seldom found on eastern white or Austrian pine, and those deposited on pitch pine do not hatch. There is one generation per year.