Key Features
- Curled brown needles on old wood
- Black-headed larvae feeding on needles
- Missing needles
Symptoms
Damaged branches resemble a lion's tail because old needles have been removed before new needles were produced. In early spring you can see scars where eggs were laid on needles during the previous fall. Young larvae are dark green and difficult to see. Needles consumed by young larvae resemble slender brown straw. As damage accumulates, more straws become visible on branches. Late instar larvae grow to one inch and are dark green with a black head and black longitudinal stripes. Other species of sawflies (red headed and white pine) differ in color feed on old and young needles and can have more than one generation per year.
Biology
Sawflies are stingless wasps that lay eggs in leaf tissue with a saw-like tail. Adults lay eggs in the fall that winter in needles surrounded by yellow halos. Eggs hatch in April into worm-like larvae when Bradford Callery pears are in bloom and begin to feed on foliage. After larvae become about 1" long, larvae make brown bullet shaped cocoons (1/2" long) that can be found along the trunk or on the ground. There is one generation of sawflies each year.
Management Recommendations
Inspect plants in early spring for straw colored needles that have been stripped by young worm like sawfly larvae. These can be easily killed by most foliar insecticides before significant damage occurs. To control sawflies without promoting later season problems with scale insects use biorational products such as spinosad, chlorantranilioprole, indoxacarb, neem oil, insecticidal soap or horticultural oil. After sawflies are one inch long they stop feeding and build cocoons and transform into adults. Sawflies regularly suffer from a lethal virus-like disease that greatly reduces their number. If you notice larvae that are hanging limp from pine needles there is no need to apply an insecticide.
Effective Pesticides
Active Ingredients include: Azadirachtin, Bifenthrin, Carbaryl, Chlorantraniliprole, Horticultural oil (Paraffinic or superior oil) , Indoxacarb, Insecticidal soap (Potassium salt of fatty acid), Lambda- cyhalothrin, Permethrin, Spinosad
