Bee Flies

They’re easy to miss! Bee flies, that is. Although common, and there are dozens of species living near us, they aren’t to be found in your neighborhood, nor will they attempt to appropriate your sandwich on a picnic. And—they don’t sting.

No, bee flies are modestly sized insects, are not colorful like bees, wasps and butterflies, and stay low to the ground, except when alighting on a flower. So, as I said, they are easy to miss. Nevertheless, I find them fascinating.

The bee fly family, Bombyliidae, contains upwards of five thousand described species. There are undoubtedly some thousands more to be described, a feature typical of many taxa with large tropical components, especially those with little recognized economic effects. And that’s for a family to which many amateur entomologists, like myself, spend time seeking out. Even so, the actual life history of very few bee fly species is fully understood. The state of our knowledge on hundreds of “lesser” tax is pitiful, indeed.

The lives of the bee flies we do know about range for bizarre to astounding. The adults are rather chunky, thin-legged, drably-colored flies seen either on the ground or around flowers. They have a thin proboscis for sipping nectar or taking pollen from flowers. In some species the proboscis is very long and held out straight in front, even when flying. Bee fly flight is distinctive in that they hover low over the ground before settling onto some sunny spot. Ah, the perfect place!

Bee fly larvae are all predaceous on other insects. Gravid females have ingenious methods of getting their eggs where they need to go; in some cases, coating her egg with fine sand grains before popping it down a mining bee’s nest hole with a flick of her abdomen. There, once the egg hatches, the first instar larva searches out its eventual host before transforming itself into a little parasitic feeding machine. When grown, the larva will pupate into the adult bee fly that will emerge from the nest hole instead of the originally intended bee.

Perhaps that will be the one you see on your next walk in the wild, as it hovers to nectar on the flower you are admiring. It won’t have the spectacular beauty of a monarch butterfly or the flower it’s visiting, but that bee fly will have taken one of the strangest journeys of any creature on earth.