For African bat bugs, the battle of the sexes is quite literally a violent struggle—and now it appears that the bugs are using gender-bending tactics to defend themselves.

 Bat bugs are small, reddish-brown parasites related to bed bugs that suck the blood of bats and sometimes bite humans.

Researchers have long known that male bat bugs ignore females’ conventional parts and instead use their sharp penises to stab the females’ abdomens, injecting sperm directly into the bloodstream.

So the females evolved a defense: structures called paragenitals that guide a male’s needle-like member into a spongy reservoir of immune cells.

But the females aren’t the only ones in need of protection. Observers documented males performing the same injurious sexual acts on other males.