#Arachtober: The #Spider Swarm!

My colleague, Chris Atkinson, told me yesterday that he’d been seeing a lot of spiders in his compost heap. “Interesting,” I thought. Then he sent me this photo:

WHOA. Look at all those spiders.

So I stopped by this morning (how could I not?), and the photo doesn’t do it justice. It is spider paradise. It’s a spider commune. There are all kinds of bugs living in the compost, and all over above them is a dense communal spider web, packed with spiders. I’d suspected it from the first picture, but I stuck my face down there and confirmed it — Steatoda borealis, the Northern Combfoot, which I’ve occasionally found while prowling about town, but this was the Mother Lode. I got a few closeups of one of their number in their web.

Then I also snatched up three of them to bring into the lab. Don’t worry, there were so many spiders there that losing a few won’t significantly affect the population.

This isn’t the best photo, but it’s got my blurry finger in the background, so you can get a sense of their size. S. borealis is a fairly large beast.

Finding a thriving population on a compost heap does have obvious implications about how these spiders might survive a winter. I took the temperature of the bin — about 10°C — which was about the same as the ambient temperature, but I’ll have to check back later when it gets really cold.

I should probably let Chris know that these spiders are venomous, though. That would be the ethical thing to do.


  1. blf says

    Got a spider in your compost heap? Call Dr “the spiders, the spiders, all the spiders!” poopyhead. Soon to be squelching through the sleet scrounging surrounding spiders…

  2. Arnaud says

    Jonathan Norburg at #2. Wasn’t that the premise of one of C. D. Simak stories in Cities? Only with ants. If I remember correctly the protagonist built a glass dome over an anthill to allow them to remember over the winter whatever progress they made during the summer.

  3. Snidely W says

    Kinda related:
    Leave all the plant debris in your garden and flower beds. Winter survival of spiders is greatly enhanced with more debris. Put off the clean up until spring. More spiders, yay!