Second to snakes, spiders are the most feared animals when it comes to phobias. They seem to have superpowers like hyper speed, materializing out of nowhere (or vanishing), invisible webs, and they’re venomous (these are the top four things I’ve gathered from people who really don’t like spiders). With all of that scariness in mind, it’s hard to think about what scares a spider. Well, they actually have a LOT to be afraid of; shoes, brooms, rolled up magazines, vacuums, bug spray, and drains to name a few. Outside, they have toads, cats, birds, nematodes, other spiders, and a myriad of arthropods who will happily devour a spider and its eggs. Some prefer to do it slowly. This latter group is what horror movies are made of – the worst nightmare scenarios, but for spiders…IT’S REAL!
One summer, not too long ago, I drove into Ohio for vacation. Once there, my car sat for the entire week. About a week after I got home, I noticed a clump of beige-colored clay attached to one of the hoses under the hood. It was small, fitting into the palm of my hand. There were two fused and sealed clay tubes, about two inches long and an inch thick. I identified it as a wasp “nest”. Curious, I decided I’d crack it open and see what was in ‘ere. Inside, I found 28 dead spiders from at least 6 different spider families. There were crab spiders, jumping spiders, ghost spiders, and orb weaving spiders all mummified. The largest spider was about 7mm, so they were all fairly small. Since I had been driving around, anything that would have been alive had been cooked, which was probably a good thing for those spiders!
From what I gathered, this was the work of a mud dauber wasp, the wasps with the long, thin waists. Mud daubers find spiders, paralyze them with their sting and then carry the bodies back to the nest. The spiders are sealed into a larval chamber where the larvae feed on the alive and helpless spiders. I don’t know what happened to the wasp larvae in this case. Perhaps they were merely eggs about to hatch until the chamber got too hot. Maybe, since larvae are soft-bodied, they cooked away from the engine heat.
There are many types of wasps that attack spiders and use them as living food for their larvae. Not all carry the spider bodies back to a nest, some simply attach an egg to the spider and leave. The spider lives, but with a maggot attached to it, feeding on it while it’s alive! There are certain types of flies that also use spiders as larval feeding packages feeding both externally and internally.
I recently caught what I believe is a Linyphiid or Sheetweaving spider along 9 Mile Run Creek in Frick Park. It is a small specimen, maybe 4mm. When I got it under the microscope, I noticed it had an yellowish larva attached to it. I had only seen this in person once before. Back in August of 2013, I caught an orb weaver with a white larva attached to its abdomen (pictured above). Since both the spider and the larva were large, I was able to carefully remove the larva with tweezers. I never found out if the spider survived because I let it go. THIS time, I’m going to observe what happens to the Linyphiid. The larva is so tiny, I don’t think I could safely remove it if I tried.
One day, I noticed the spider was eating a fruit fly. I popped the spider’s container under the scope to check it out and to see if there were any changes with the larva. The larva looked bigger, but I wasn’t sure. I wondered if the spider could feel it. The spider seemed to be going about its business with no notice of the attachment.
But that’s not even the worst part. Under 20x magnification, I could see the spider’s face as it was eating what was left of the fly. And I saw something else…tiny, spined legs were slowly moving near the spiders chelicerae (fangs). In that moment, the spider released the fly ball revealing MITES! Not one, but THREE mites were gathered under the spider’s clypeus. The clypeus is the area between the eyes and the chelicerae, an area where movable, soft parts can be penetrated. At least two of the mites seemed to be embedded. I wasn’t able to find out if the mites were parasites or just hitchhikers. The spider used its palps to try to brush the mites away, but it didn’t work. They were somehow attached!
So far, the spider is doing normal spider stuff, but I’m thinking it has little chance of getting out of this predicament. The spider may have been infected while in the egg sac or caught while out and about.
Here is a video of what happened to a wolf spider with a wasp larva attached to it. There are other videos like this floating around online if you so wish to search them. The nematode bursting out of the dead spiders is really crazy…
So, spiders have their fair share of dangers out there in the world. They are susceptible to being eaten by their own kind, killed by people just because they were crossing their path, and pecked by hungry robins, but that’s the easy way out, the PG version. The real horrors are the parasites we don’t even notice slowly eating away at the spiders while they are still alive! It puts the movie Arachnophobia to shame. All they had to do was release some wasps…