Scoliidae: Scoliid Wasps

Biology

The family Scoliidae is composed of fairly large, stout-bodied wasps, usually brightly patterned in red and yellow or white, sometimes in combination with black.  Scoliids are external parasitoids of soil-inhabiting scarab beetle larvae, but as adults they visit flowers and feed on pollen and nectar.  Some species are quite hairy which aids in pollination.  Some female scoliids use the scarab’s own burrow as a nest instead of digging a new one.  When a female wasp finds a scarab larva she stings it into paralysis, and then she either lays an egg on it or moves the larva deeper into the soil before laying an egg on it.  After hatching, the scoliid larva feeds on the scarab host for one to two weeks and then spins an underground cocoon in which it pupates and overwinters.  There are only 20 species of scoliid wasps in North America and we have three in the Pacific Northwest.