Bombyliidae is a large family of flies with hundreds of genera, although their life cycles are not well known. Adults generally feed on nectar and pollen, thus are pollinators of flowers. They superficially resemble bees and are commonly called bee flies. This resemblance may offer the adults some protection from predators.
The larval stages are predators or parasitoids of other insect eggs and larvae. The adult females usually deposit eggs in the vicinity of possible hosts, quite often in the burrows of beetles or wasps/solitary bees. Where most often in the insect world parasitoids are highly specific in the host species that they will infect, some bombyliids are opportunistic and will use a variety of hosts.
While bombyliids have a great variety of species, rarely are individuals of any one species abundant, and this is perhaps one of the poorest known families of insects relative to its size. There are at least 4,500 described species, and probably thousands as of yet undescribed.