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When you hear the word ‘caterpillar’, you probably think of a hungry little chubby-grubby thing happily chowing down on some leaves. But the Hawaiian inchworm, also known as the ambush caterpillar, might change your mind.

Because when it arrived in paradise, it ditched the peaceful vegan diet for razor-sharp claws, a sensitive hair trigger, and a taste for meat. Specifically, live bug meat. The first thing that’s weird about these guys is that islands are often home to gentler forms of life—a tendency known as island tameness.

That’s because the vast majority of species don’t make the dangerous trek across waterways. So those that do find themselves in a habitat free from their usual competitors and predators, where they can start a new, more relaxed lifestyle. Hawaiian raspberries ditched their thorns, for example.

No point in being thorny if there are no mammals you need to fend off. Somehow, Hawaii’s inchworms didn’t get the memo. For them, the lack of insect eaters was an opportunity—there were just so many bugs around, and pretty much no one else was eating them.

They were already used to a somewhat protein-rich diet because of their fondness for pollen over leaves. And, like other caterpillars, they were equipped with powerful jaws for chewing tough plant material. At some point — probably within the last hundred million years or so — they started using those jaws to chew insects instead.

No one noticed these caterpillars’ unusual eating habits until the 1970s, when a biologist named Steven Montgomery saw one chewing on a fly. Slightly confused, he brought the animal back to the lab. For two days, it just sat there, and didn’t take so much as a single bite of the leaf it clung to.

So on a hunch, he threw a fruit fly in with the caterpillar. And then the fly made the mistake of bumping into the caterpillar’s backside. There are other inchworms that rear up and snap their bodies defensively.

But when prey touches a Hawaiian inchworm, it goes on the attack, whipping around to grab its meal with the six long, sharp claws attached to its legs. After that, it’s all over for the prey. Even though it’s probably not dead yet, it’s lunchtime for the caterpillar.

There are a few other types of carnivorous caterpillars, almost all of which are native to Hawaii. But the ambush caterpillar is definitely the most violent. A close second is probably H. molluscivora, which eats snails by wrapping them in silk while they're sleeping, then eating them alive once they can’t escape.

Which is less violent, but more creepy! But at least it’s not a living whip with terrifyingly sharp claws. So thanks, Hawaiian inchworms, for the nightmares.

And thank you for watching this episode of SciShow! If you love learning all about the bizarre world we live in, you can keep up with our latest episodes by going to youtube.com/scishow and subscribing. ♪.