This is one of several species of leaf beetles in this genus. Willow is the favored host plant, but they also feed on cottonwood, alder, and other trees. The adult beetles overwinter on the bark or under materials on the ground and emerge in early spring. Eggs are laid and the larvae feed through the spring months, usually in clusters of many young larvae and on the undersides of the leaves, moving apart as they get older. Heavy feeding will cause the leaf to be skeletonized and to fall off the tree. Adult beetles also feed on the leaves. The larvae can emit a foul smelling fluid from glands along the sides of the body when they are disturbed, and this appears to repel most predators. There may be 4 generations each year, with the first generation causing the most damage to ornamental trees.
Leaf beetles can be killed with applications of residual insecticides made when the larvae or adults are present on the foliage. Systemic insecticides applied to the soil are also very effective by moving the active ingredient up the tree and into the foliage to be eaten by the feeding beetle larvae. This application needs to be done well in advance of the presence of the larvae to give the active ingredient time to move up from the soil.