Introduced pine sawfly (Diprion similis)
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 introduced pine sawfly prefers the foliage of white pine, although it occasionally attacks jack, red, and Scots pines as well. The first generation feeds on old foliage, while following generations consume both old and new foliage. Young larvae feed on only the tender outer parts of the needle. Mature larvae, which feed individually, consume the whole needle and also may chew on tender bark. Complete early season defoliation kills branches and entire trees.
Larvae are present from late May to early July, and again from August to September. The mature larva has a black head and a dark-brown body with a double black stripe down the back and many yellow or black spots on the sides. The first generation pupates in cocoons spun on the tree, while later generations pupate both the in the duff and on the tree. Pupation is completed in early spring. Adults deposit eggs in slits cut along the edges of old needles. There is usually a second, and under favorable conditions, a partial third generation each year.