Sawfly Control Sawfly populations are usually controlled by combinations of natural enemies, predators, starvation, disease, or unfavorable weather. In other cases, entire branches will be without needles or only short stubs of needles will be left. Younger larvae eat the outer edges of pine needles leaving behind the central tissue which wilts and dies to creating the appearance of dried straw, making sawfly damage distinctive. Insecticidal soaps, horticultural oil, and pyrethrin are labeled for sawfly control. Remaining needles will be reddish brown. Bt (Bacillus thuringiensis), which is an effective natural control for true caterpillars, is ineffective on sawfly larvae. The nuclear polyhedrosis virus of N. sertifer represents an effective, selective and safe biological control agent. However, Hymenoptera Symphyta. To control sawfly larvae, try to choose the method or product least harmful to other insects. The speed and high rate of deaths of larvae infected with NsNPV indicate that it is a very promising agent for biological control of the European pine sawfly. The introduced pine sawfly (Diprion similis) larva is about an inch in length, yellowish green with two black stripes down the back with mottled sides, and a black head. The natural insecticide spinosad will control sawfly larvae. Conventional insecticides such as malathion are also effective. Sawflies Facts, Identificatio,n & Control Scientific Name. The best time to control sawflies is early in their larval stage. Regular inspection of pines will help to detect sawfly infestations before the larvae reach a size that can cause Older larvae eat the entire needle, and if complete defoliation occurs, groups of larvae will move to the nearest acceptable food source and continue feeding. Appearance What Do They Look Like? Pine sawfly attacks are sometimes recognized when just one side of the needles have been destroyed by the larvae eating the pine needles. Size: Sawfly adults are about 1/2 inch long. Or look for pupal cases on or near the plant and destroy them. Characteristics: Sawflies may look like flies, but are actually related to bees and wasps.The common name sawfly comes from their ovipositor, which is saw-like in shape and is used by the females to cut into the plants and lay eggs. The larvae feed primarily on white pine and other five-needle pines, The white pine sawfly ( Neodiprion pinetum ) larva is cream color with four rows of black spots on the body and a black head. Outbreaks can occur when natural control does not produce high mortality. Sawfly larvae are easily knocked off plants, and can be dropped into soapy water to finish them off.