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)
Pine sawflies defoliate many species of pine, causing tree or branch mortality and growth reduction. These sawflies can be classed generally as "spring" or "summer" species:
European pine sawfly
Red pine sawfly
Jack pine sawfly
Virginia pine sawfly
Introduced pine sawfly
White pine sawfly
Redheaded pine sawfly
The spring species commonly feed only on old foliage, giving trees a tufted appearance with new foliage only at the branch ends. The summer species generally feed first on the current year's foliage, then attack older needles. This causes greater growth reduction and tree mortality.
Dried, skeletonized groups of brown needles are an early symptom of sawfly infestation. These needles generally drop from the tree soon after being killed. Older larvae consume entire needles, stripping the tree branch by branch.
The life history is similar for all sawfly species. Eggs are deposited in the needles and new larvae feed in groups. Mature larvae, from ¾ to 1 inch long, from brown pupal cocoons of tough woven silk. Pupation usually occurs in the duff under the host tree, although some species may pupate on the tree. Sawflies overwinter in the prepupal stage within the cocoon, or as eggs in needles, The number of generations per year depends on species and location.