Two beetles cause most of the “what is this bug” confusion in American gardens every summer: the June bug and the Japanese beetle. The Japanese beetle is smaller, about 3/8 inch long, with a metallic green head, coppery bronze wings, and a row of five white hair tufts on each side of its abdomen, and it feeds in daytime groups that can skeletonize a rose bush in days. The June bug is larger, reddish brown to nearly black, flies clumsily at night toward porch lights, and causes only minor, scattered leaf notching. Getting the ID right matters because the two…