It happens at least once or twice every year; someone finds a brilliant metallic green beetle in a corn or soybean field and asks if it is a pest. The dogbane beetle is fairly large for an Iowa beetle, about 3/8-1/2 inch in length, but it feeds only on dogbane and milkweed. The larvae feed on the roots of these two plants; therefore, this insect is fairly common along roadsides, in pastures, and grassy filter strips in fields where these plants grow.