This mimicry of bees and wasps is not unusual in robber flies. In the pines and firs just above the grasslands here live several species of robber flies called Laphria . It takes practice to tell them from bumble bees, because they are big, fat, and densely clothed in various combinations of black, yellow and red hair. White-tailed Efferia buzz everywhere. Females probe cracks in the soil with sword-like abdomens, searching for the best places to lay eggs.
Most robber flies grow up in the soil, where the larvae hunt other insect larvae and pupae.
A few years ago, over the hills to the northeast, at Vaseux Lake, I discovered an unknown species of Efferia . Actually, I first found specimens mixed in with those of a closely related species in the Canadian National Collection in Ottawa. They had been collected years ago, but the collection data led me to their true habitat. This species lives where there is sandy soil rather than clay, and eggs are not laid directly in the soil but are instead delicately inserted in the dried flower heads of bunchgrass. I am naming the fly Efferia okanagana after the only place it is known to exist.