European pine sawfly larvae are present throughout the state feeding on Scotch, mugo, and other two and three needle pines. The larvae grow to about one inch long with dark and lighter green stripes. They have large black heads. Sawfly larvae can be distinguished from caterpillars by having six or more pairs of prolegs.
They drop to the ground to pupate as first year needles are breaking from the candles. As such, their defoliation is not a serious threat to tree health, but the mostly bare stems left behind reduce aesthetic appearance.
Because the larvae feed in groups, hand-picking is an effective control. Spraying with acetamiprid (TriStar), azadirachtin (Azatin, Bioneem, Ornazin) or spinosad (Conserve) is also effective.
Photo Credit Phil Nixon