Health Protection, Southern Region
BLACKHEADED PINE SAWFLY,
Neodiprion excitans Rohwer
Importance. - This sawfly, which ranges from Virginia to Texas, prefers loblolly and shortleaf pines but also feeds on slash, longleaf, and
pond pines. Because heaviest defoliation occurs during late summer and fall, trees may go through the winter stripped of their needles. The resulting loss in
vigor may predispose slow-growing pines to bark beetle attack.
Identifying the Insect. - Older larvae are about 1 inch (25 mm) long and olive green with a glossy black head. Two longitudinal black
stripes run along the top of the body, and a conspicuous row of black spots occurs on each side. The adult female is about 1/2 inch (12 mm) long with a light
brown body. She lays her eggs singly at the bases of needles on the tips of shoots.
Larvae. (Click for detail. JPG 41K).
Identifying the Injury. - Defoliation during spring and summer is not serious because larvae tend to feed on the older foliage. In the
fall, however, defoliation may exceed 90 percent of the total crown and result in a considerable growth reduction during the following season. Heavily defoliated
trees, especially overmature sawtimber, may be killed following secondary attacks by bark beetles.
Biology. -The larvae overwinter in light brown cocoons spun principally in duff, topsoil, and bark crevices at the base of the trees. Pupation
is completed in the spring, and both adults and larvae are sometimes present throughout the summer and fall. There are 3 to 4 generations per year in the Gulf
Control. - Outbreaks of the blackheaded pine sawfly occur periodically and usually subside rapidly. Natural enemies are usually helpful
in preventing or ending outbreaks. Insecticides may be warranted on high value trees.