Plagiodera versicolora, which is a pest of most willows and poplars. This beetle is pri-marily a problem in the northern third of Illinois. If left unchecked, this beetle can cause severe aesthetic damage to plants in landscapes.
Adults are black to greenish blue.
The adults hide during the winter under loose bark or in protected places on the tree trunk. In spring, they feed on foliage and lay glossy, pale-yellow eggs on the underside of leaves. The larvae cause the most damage as they feed on the leaf tissue, leaving only the leaf veins. After feeding, the larvae enter into a pupal stage, which generally lasts 3 to 4 weeks. There may be two to three generations per year.