European pine sawfly larvae feed in clusters on the old growth needles of mugho, Scots and red pine trees and shrubs. Larvae are grayish-green with 2 light stripes and 1 dark stripe on each side of the body and shiny black legs and head. Full grown larvae, usually present by Memorial Day weekend, are about 1 inch long. 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. Spraying is of greatest benefit when done before the larvae become one-half grown. Iowa State University , Ames, Iowa. This information subject to a usage policy .