The female fastens rose-coloured eggs to long, slender stalks. In most species, the larvae parasitize eggs and young of spiders. Newly hatched larvae are active and have well-developed legs and a squarish head. These active larvae locate and enter the spider's egg case. Once inside the egg case, they molt into a fat white grub with short legs that consumes both eggs and newly hatched spiderlings in the egg case. The fully grown larva (7 to 10 mm long) spins a silken cocoon before its first pupal stage. Some species have an unusual, active second pupal stage with no cocoon. The larvae of the Brazilian mantispid (Symphasis varia) are parasitic on wasps and pupate in the wasp nest.