In the normal course of things, beetles will generally stick to eating insects, worms, and any dead meat it happens to come across. But if conditions are right, one species will kill and devour frogs many times its own size.
What's worse, the Epomis beetle likes to become best buddies with its amphibious prey during the day, then eat it during the night. It's particularly unexpected because things should be the other way around, with frogs and toads preying on these beetles. Yet every single time researchers placed a frog and a beetle together in an enclosure, the result was always distinctly unpleasant for the frog.
Researcher Gil Wazen of Tel Aviv University explains:
"Amphibians are typical insect predators, and their diet may include adult beetles, ground beetles in particular. The recently filmed successful attacks of the beetles on toads and frogs brought new insights on the amphibian-insect interactions, and documented the uncommon phenomenon of invertebrates preying on vertebrate animals."
The beetle shares shelter with the frog during the day, apparently luring it into the animal equivalent of a false sense of security. Then, come nightfall, the beetle bites into the frog, injecting it with a toxin that leaves the frog - or any of a number of other potential amphibian, the Epomis beetle doesn't care - completely paralyzed. At that point, the beetle starts slowly devouring the frog over several hours, starting with the legs.
There's no clear explanation for how the beetle manages to reverse the usual predator-prey relationship, but I think we can say this much - we may have just found the insect equivalent of the honey badger.