by Shaila Palamand
At a glance, this looks like a bumblebee. It also sounds like a bumblebee, and flies like a bumblebee.
But this is not a bumblebee – it’s a bee-mimic robber fly, a member of the Asilidae family, specifically in the Laphria genus.
Perhaps you would prefer to see an actual bumblebee rather than a mimic. After all, bumblebees are incredibly important to our ecosystem, playing a critical role in the pollination of flowering plants and a wide variety of crops. The bee-mimic robber fly, on the other hand, doesn’t copy a bumblebee’s precious pollination behavior, but only emulates its general appearance and sound. One might say that imitation is the sincerest form of flattery; but in the robber fly’s case, it’s more likely a survival mechanism. Looking and sounding like a bumblebee might help to ward off its potential predators. Still, the robber fly is an interesting insect to observe, and does have its own place in our ecosystem.
Asilidae is a sizeable family; there are over 7,000 species of robber flies worldwide, 250 of which are found in Texas. In particular, members of the Laphria genus are known for being bee-like in appearance. Robber flies are predators, typically hunting for large, flying insects. They are not very selective in that regard, sometimes consuming beneficial insects such as butterflies and even bumblebees! However, on the positive side, they also consume wasps and many pest insects that damage crops. Overall, the hunting practice of robber flies helps to maintain balance in the insect population, which in turn benefits other aspects of our environment.
The robber fly’s alternate nickname, “assassin fly”, was likely inspired by its hunting style. It waits and watches for flying insects, pouncing when the moment is right. It usually catches its victim in mid-air, using its long legs to secure and stabilize it. The robber fly then injects an enzyme that both paralyzes the victim and dissolves its insides, and uses its stout proboscis to extract the liquid from its prey.
Bee-mimic robber flies aren’t uncommon in East Texas, so it’s possible that you’ve already seen one. But its clever costume can initially be deceiving, so if you see a black and yellow fuzzy thing buzzing around and aren’t quite sure if it’s an impostor or the real thing, here are a few quick ways to determine that it’s a mimic:
- Yellow fuzz on its face, in the shape of a “mustache” and “beard”
- Only two wings (whereas bumblebees have four)
- More tapered abdomen than a bumblebee (especially males)
Robber flies prefer open areas, but can also be found along forest edges. They are more likely to be perching and watching for prey than hopping from flower to flower like a busy bumblebee.
If you’re interested in learning more about these fascinating insects, check out these great resources:
https://robberfly.org/laphria/
https://aggie-hort.tamu.edu/galveston/beneficials/beneficial-27_robber_flies.htm