Sawfly
Sawfly larvae on a poplar leaf
About Sawfly
Lives on willow, cottonwood, and other poplars. Color of larvae depends on the species present, and may vary from black or greenish-black to light green with rows of yellow or dark colored spots along sides of the body. Adults resemble small bees.
Adult sawflies emerge during spring and lay eggs in pockets cut in leaf tissue. Larvae feed gregariously on leaves during the summer and then drop to the ground to overwinter and/or pupate. There may be more than one generation per year. When distrubed, larvae curl up in a characteristic "s" or "c" shape. Large infestations can cause substantial defoliation.
To Control
Spray larvae and leaves with malathion or carbaryl.