A worm-like larva grows inside the egg, and when it is ready to emerge, the larva chews a small hole in the egg and wiggles itself out. The first meal a larva will have is the milkweed leaf.

RIO GRANDE CITY, Texas— The U.S. Fish and Wildlife Service today protected the prostrate milkweed as endangered. Only 24 populations of the plant survive, in south Texas and northern Mexico, where ...