Emerald Ash Borer

Like all beetles, the emerald ash borer undergoes complete metamorphosis (is holometabolous) with four life stages: egg, larva, pupa, and adult. Adults are a dark green metallic color and approximately ½ inch long. They are the only Agrilus species in North America known to have a bright metallic coppery-red (may also appear purple) dorsal surface of their abdomen. (The wings must be lifted to see that feature.) Larvae are white, 1 to 1.25 inches long at maturity, have a small brown head, a pair of brown pincers at the end of the abdomen, and have bell-shaped abdominal segments. The fourth instar larvae overwinter in a pre-pupal stage in a J-shaped position. Pupae are present in the spring and look like cream-colored adults that begin to darken as they develop. The larval and pupal stages are found beneath the bark of their host trees, as the larvae feed on the nutrient and water conducting tissues of the plant. Adults emerge in May and June and mate and lay tiny, flat, oval shaped eggs that are initially whitish-yellow in color and turn reddish-brown as they develop. Eggs are difficult to see as they are approximately 1/32 of an inch and laid in cracks and crevices of the bark. On average, females can lay 55 eggs in their lifetime, but some have been observed laying more than 150 eggs. Adult emergence creates D-shaped exit holes in the bark.
(University of Massachusetts)