Wildlife Watching Wednesday: The Predatory Bee-Mimic Robber Fly

By: Tom Berg

In nature, there are many creatures that mimic other creatures – for one reason or another. This is especially true in the insect world. Often, insects try to look like another species of insect that is poisonous or tastes bad. That might keep birds or other predators from trying to eat them. 

Some other insects try to look or act like a more dangerous insect so that other creatures will stay away from them and not attack them. One of these is the Bee-Mimic Robber Fly. This fly looks very similar to a common bumblebee, and since bumblebees pack a nasty sting they are often left alone – by other insects and by people!

Also called the Bee-Like Robber Fly, this insect is black and yellow like a bumblebee and is similar in size. A member of the Laphria family (or genus), there are more than 30 species of robber flies in the eastern United States. Since they are actually a fly and not a bee, they have no stinger. They do not collect pollen, either.

Instead, the bee-mimic robber fly attacks and eats other flying insects, especially wasps and bees. It also eats beetles, moths, grasshoppers and other insects. In place of a stinger the bee-mimic robber fly has a very sharp proboscis that it uses to impale its prey. It then injects them with powerful digestive enzymes which liquefies the victim, and the robber fly consumes the liquid.

Robber flies like this one are also sometimes called “assassin flies” because of their deadly behavior. They like to sit on a leaf at the edge of a clearing in the forest and wait for a likely victim to fly by. When they see it, they fly out and grab their target and quickly kill it. Bee-mimic robber flies are deadly predators.

Although the bee-mimic robber fly cannot sting, it can certainly deliver a painful “bite” with its proboscis. So here are a few words to the wise: avoid the urge to pick one up and handle it!

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