What Eats Spiders?

One odd little tradition I have with my son when I pick him up from preschool is the “tickle spider game”. It goes like this. He climbs up on the railing that runs down the sidewalk, and begins scooting along it. I put my hand on the railing behind him and scurry it after him like a bug, all while shouting “tickle spider’s gonna get you!”. He laughs, and makes it to the end of the railing and declares it base. Then, if traffic is clear, he sprints to the car while I pursue him. “Tickle spider’s gonna get you!”

It’s silly, yeah. But it’s evolved into a thing we do.

One day, after we do this and I’ve got him belted into his booster seat, he starts telling me about how some spiders have big, hairy heads. I’m not positive why this comes up, but spiders are on his mind because of the game. And I think that someone may have brought a tarantula into his class as well, so he’s thinking about big, hairy spiders at the moment. And then he asks his question:

“What eats spiders?”

Well, I can answer that in part. So I tell him that bugs eat spiders, and birds, and frogs. He answers “no”, and proceeds to tell me that dogs eat spiders. And then he’s off talking about Luke Skywalker, because he’s five.

So what *does* eat spiders? The answer, according to a few different web sites, along with Rainer Foelix’s Biology of Spiders, the answer seems to be “lots of things”. This includes the usual suspects – frogs and toads and lizards and birds and insects – and a few that I never once thought of as preying on spiders. Monkeys, for instance. Or other spiders. Ants as well, which just gives me a horrible mental image of a swarm of ants rolling over a spider and tearing it to pieces (fair warning:  don’t click that link if you’re afraid of spiders, or of ants). But two spider predators really stand out. The assassin bug, and the spider wasp.

This is an assassin bug:


An assassin bug hunts by finding a spider web. It then begins plucking the web in a pattern that simulates struggling, exhausted prey. When the spider comes to investigate the assassin bug gets into position and stabs it with its proboscis, injecting either venom or digestive acids (depending on the species). Once the spider dies, it settles down to dinner.

They’ll also bite people. The bug is too small to kill a human, but the bite does transmit a parasite called Trypanosoma cruzi, which is responsible for something called “Chagas disease“, most commonly encountered in Latin America. The parasite results in skin lesions and/or purplish swelling of eyelids, fevr, headache, enlarged lymph glands, muscle pain, abdominal or chest pain, and difficulty breathing. If left untreated, it can also result in death from destruction of the muscles and nerves of the heart.

So, yeah.  Maybe they can kill humans.

And then there’s the spider wasp:

spider wasp

“Spider wasp” is actually a common name for the Pompilidae family of wasps, consisting of around 5,000 species. Why are they called “spider wasps” you ask? Well, you may have heard about this before, but spiders are an important part of their reproductive cycle. The spider wasp female digs a burrow, then locates a spider. She paralyzes the spider by stinging it, then drags it back to the burrow and lays an egg on it. The paralyzed spider is then stashed in the burrow, where the egg hatches and the wasp larva consumes it.

Not all spider wasps dig burrows, though. Some will just paralyze the spider and let it lie, with the egg on it. Either way, it sucks to be that spider.  But hey, at least there’s no evidence that dogs will eat them.