Two of these photos arrived this week with the same question, “What is eating my bees?” The top photo, taken by beekeeper Wayne Gillispie, came from northeastern Kentucky. The second, by beekeeper Roger Taylor, came from Gallatin, Tennessee. Each predator has a honey bee in its jaws.
These creepy-looking bugs are in the family Asilidae and are commonly known as robber flies or assassin flies. Based on the photos, it might seem like they have a predilection for honey bees but, actually, just about any insect will do for a midday snack.
Feasting on insects
The family is huge, comprising about 7000 species, and they all eat insects. Many of them enjoy meals that are large and feisty, so they will go after dragonflies, wasps, bees, grasshoppers, butterflies, moths, and beetles. Most have spiny legs that aid in capturing prey in the air and holding it still.
Once an insect is captured, the fly stabs it with its proboscis and injects paralyzing enzymes. In time, the enzymes digest the insides of the prey and the robber fly sucks it out, like coconut milk through a straw…or a protein-fortified smoothie.
Incidental predators on bees
Robber flies occur nearly everywhere, but more species are found in places that are open, warm, and sunny. They are only incidental predators on honey bees and nothing for a beekeeper to worry about. Just keep taking those cool photos.