Robber flies

Robber fly eating a small white moth

I've had the fortune of seeing quite a few robber flies this year (I first discovered these guys two summers ago). Though seemingly nondescript, they're among the most gruesome of all predators. Relying on surprise, robber - or assassin - flies, lay in wait for an unsuspecting prey to come along and then ambush them, taking the insect out of midair.

Butterflies, moths, and many other nectar-loving insects have long, spindly and bendy proboscises. Not so the robber fly, whose short and hard proboscis is thrust into the body of their prey. It's hard to make out in the photo, but they have a bristly mustache on their face that is potentially a face mask that protects them as their prey flails about.

Then like a shrew, they inject the unfortunate insect with a neurotoxin that paralyzes it and, like a sea star or spider, follows up with an enzyme that liquefies the prey's innards. From there, they make an easy job of slurping up the slurry of guts.