The name, bee fly is commonly applied to numerous species of flies that resemble bees. Bee flies are some of the earliest pollinators to appear in Spring. Bee flies can be seen hovering in front of flowers, feeding on the nectar. The long mouthparts of adult bee flies are used to reach deep into narrow flowers to collect nectar that is not available to insects with shorter mouthparts. Bee flies are important pollinators of wild flowers.
Bombylius major, is one of the largest bee flies in Indiana. It is abundant this spring (2012) and populations usually persist through late spring. Bombylius major larvae are parasitoids of ground dwelling bees and wasps. The female bee fly cannot enter the nest to lay her eggs. However, the resemblance to bees allows the adult female to make a close approach to the nest entrances. From a safe distance, the female will flick eggs into the nest entrance. A larva will hatch from the egg, crawl into the nest and wait in a cell that contains a developing bee. When the bee pupates, the bee fly larva will hatch and consume the bee pupa. The bee fly will pupate and overwinter in the bee nest.