Ah, there's nothing that makes a good horror movie or sci-fi flick like the living dead. So it's no wonder that this little fly makes it on my list of sci-fi-worthy parasites. It's claim to fame is that it eats the brains of ants while turning them into living zombies for a bit before decaptating the unfortunate insects and moving onward.
Yeah, they're pretty bad ass.
These flies, from the genus Pseudacteon, are small and resemble fruit flies. They are quite different, though, in life cycle and behavior. As adults, they've earned the name "scuttle fly" because they tend to run on a surface away from a potential threat instead of flying. But it's the larvae that are the little monsters responsible for headless ants worldwide.
The adult female uses a sharp egg-laying organ called an ovipositor to inject her eggs into an ant's body cavity. From there, the larvae hatch and make their way to the ant's brain. There, the happy parasite feeds on the ant's hemolymph (ant blood), muscle and nervous tissue (a.k.a. braaaaaaaaaaaiiiiiiiiiiiinnnnnnsssss). Eventually, the fly-to-be completely devours everything inside the ant's head. The ant, meanwhile, wanders around as if it still had its brains for around 2 weeks. Eventually, when the larva is ready to pupate, it releases an enzyme which decapitates the ant by dissolving the membrane which attaches its head to its body. The fly larvae pupates in the ant's disembodied head for about 2 more weeks, then emerges as a full-grown adult fly.
What's even better about these parasites, in my book anyhow, is that they've recently been targeted for use as biocontrol of fire ants in the southern USA. If you've ever been bitten by a fire ant, you know how absolutely retched the little buggers are. Bites hurt and itch like crazy, and the ants are almost impossible to erradicate by natural means. You can't flood them out - they build a raft on the corpses of the dead and merely float to the nearest above-water object, which they scurry up (FYI: if that object is you, it's one of the worst exeriences imaginable). They also cause a lot of damage every year because of their inexplicable attraction to electronics. Fire ants cost the Texans alone about $1 billion annually by damaging circuit breakers and other electrical equipment, according to Texas A&M.
Anyhow, scientists are introducing several species of these Phorid flies to serve as biocontrol of the fire ant populations. I sincerely hope they succeed. The more headless, zombie fire ants, the better, if you ask me.
Mother Nature couldn't let those wonderful wasps be the only ones that get to have the joy of turning creatures into zombies... Let's just hope that none of them figure out how to use us as hosts.
But if someone you know starts wandering around aimlessly and acting like his or her brains are being devoured slowly, you know what you have to do... to save humanity.