Defoliation of pine trees and shrubs by clusters of European pine sawfly larvae should be apparent by now. Larvae of this common pest species are grayish- green with 2 light stripes and 1 dark stripe on each side of the body. The legs and head are shiny black. Full grown larvae will be about 1 inch long.
The larvae are gregarious and stay together in a cluster as they feed on the old needles from mugho, Scots and red pine trees and shrubs. Because only old needles are eaten and not the new, emerging growth, defoliated trees are generally not killed. Damage may be aesthetically displeasing, especially in Christmas tree plantations, and growth of the tree may be stunted.
Control can be as simple as pruning off and discarding infested branches. Heavier infestations on larger trees may justify foliar sprays of Sevin, Orthene or Isotox.
This article originally appeared in the May 25, 1994 issue, p. 81.