Sawflies are the only members of Hymenoptera that ffed on plant tissues. The larvae look like caterpillars of butterflies and moths. Pine sawflies can cause severe defoliation of pines. When defoliation occure in the fall, the trees may not have time to grow new needles and thus go through the winter barren of foliage. The resulting loss in vigor may make the trees susceptible to tree killing bark beetles and other wood boring insects.
All pine trees grown in Texas are susceptible to attack.
The usually attack larger trees but will defoliate ssedlings or sapling trees. Damage the newly hatched larvae feed close together. Often there may be 50-100 feeding in a group. Young larvae eat the outer tissue of the needles while older larvae eat the entire needle thus causing the defoliation. The insects are most active during late summer or fall.