It looks like a bee and sounds like a bee... but it's not a bee

I've written about mimicry of bees by flies before, in context of syrphid flies. Syrphid flies are generally considered Batesian mimics, which means, broadly speaking, that they mimic a more harmful creature. In the case of syrphid flies, they are mimicking stinging insects like wasps and bees, and thereby get to piggyback on the anti-predator defenses of those species. This kind of mimicry can only work if the creature being mimicked signals its ability to harm a predator in some way that can be imitated.

What I'm writing about today is a bit different. I managed to snap a picture of a bumble bee-imitating robber fly last week in my local ravine park. Although it's possible that the bumble bee-imitation confers some anti-predation advantages to the robber fly through Batesian mimicry, something else is probably also going on here: Wicklerian-Eisnarian mimicry. The idea with this kind of mimicry is that an organism imitates a less harmful one in order to avoid detection by its prey. Robber flies prey on other insects, including bees; looking a lot like a bumble bee is probably a pretty good way to get close enough to their prey to kill them, since bees are nectar and pollen eaters rather than insect eaters. From the perspective of many insects, a bumble bee is no particular threat, while a robber fly is definitely worth avoiding.

There are many other types of mimicry besides these two, as well. I was rather pleased to get a picture of a bee mimic that isn't a pollinator but rather a predator. Pretty neat! They also sound a lot like bumble bees, interestingly, so the mimicry goes beyond visual cues in the case of this robber fly, which I think is in the genus Laphria, and which has caught an emerald ash borer (Agrilus planipennis). Robber flies consume their prey by piercing their bodies with a hardened tube that serves as their mouth, through which they inject their prey with some digestive enzymes and then suck out the delicious bug juice that results.

Laphria sp. consuming Agrilus planipennis (sorry for the crummy cell phone camera photo)

Mmm, bug juice.