We don’t normally think of flies as being particularly badass. Annoying and filthy maybe, but nobody’s ever run screaming out of a room at the sight of one flying in through the window. Well maybe if it was a tsetse fly. Or looked vaguely like Jeff Goldblum.
Anyways, there actually is one kind of fly that’s just as voracious of a predator as any savage jungle cat or surfer-mangling shark. They’re called robber flies. Or, if you want to be more accurate about them, you can use their other name: assassin flies (Source #1).
But enough with all that technical stuff, let’s get to the murder. With all their predatory adaptations, robber flies are fully capable of taking on some rather unexpected prey (Source #6), such as…
Wasps and bees:
Dragonflies much bigger than themselves:
And even spiders in their own freaking webs:
And just like any proper serial killer, robber flies stab their victims to death. After seizing their prey, they shove their short, sharp proboscises into their victims’ flesh like an oil can spout, inject a paralyzing toxin that liquefies the insides, and then suck out the goop like a straw (Source #7). They’ll gleefully and painfully stab your ass as well, if you annoy them enough.
Just in case you were having trouble picturing the aforementioned puncturing and goop sucking, here you go:
—- Sources —-
Source #1: Few insects will mess with a nest of hornets. That is, few except the notorious robber — aka assassin — fly.
Source #2: The mystax helps protect the head and face when the fly encounters prey bent on defense.
Source #3: All robber flies have 3 simple eyes (ocelli) in a characteristic depression between their two large compound eyes. The antennae are short, 3-segmented, sometimes with a bristle-like structure called an arista. Their eyes are set wide apart for good depth perception, with even a depression between the eyes to allow full sweeping vision.
Source #4: That bright yellow structur under the main wing is a haltere. Most insects have two sets of wings and we can tell quite a lot about where a given species fits in the insect scheme based on how it uses those two. Dragonflies and damselflies use both for flying, in beetles the forewings are “sclerotised” into a rigid case that protects the flight wings and the “true flies” ( order Diptera) have turned thier hind-wings into halteres – greatly reduced wings which act as gyroscopes stabilising the flies’ flight and allowing them to perform aerobatic tricks.
Source #5: Larval and adult robber flies are predators of other insects. The adults are famous for their ability to capture prey in the air. In fact, robber flies will often catch insects that are larger than themselves, such as bumble bees.
Source #6: The robber flies are an abundant and diverse family (Asilidae) known for their predatory behavior. As their common name implies, robber flies have voracious appetites and feed on a vast array of other arthropods, which may help to maintain a healthy balance between insect populations in various habitats (Joern and Rudd 1982, Shurovnekov 1962). Asilidae adults attack wasps, bees, dragonflies, grasshoppers, other flies, and some spiders.
Source #7: They inject a neurotoxin with their proboscis that renders the quarry helpless, while its insides liquefy.
Source #8: Explanation of Names
Diogmites Loew 1866
from Greek διωγμοσ ‘chase, pursuit’
The common name was suggested by Herschel Raney after Dogmites’s habit of hanging by its forelegs while consuming prey.