Lygaeus kalmii, commonly known as the milkweed bug, is a species of true bug belonging to the family Lygaeidae. It is found in North America, particularly in areas where milkweed plants grow. These insects have a distinctive red and black coloration, with a flattened body and long antennae. They feed primarily on the seeds of milkweed plants and are known to exhibit aggregative behavior, often forming large groups on milkweed pods.