Tuesday, November 24, 2015

Eggs in a blanket

A few weeks ago, searching for spiders for Arachtober, when we post a spider a day to the Flickr pool, I found a pretty, chocolatey cobweb spider under a brick, and brought her inside. I put her in a glass box, and she quickly made herself at home, building a messy web in the corner, and settling in to wait for sowbugs, her favourite food. I'd removed the brick, so I let her stay in the box, and have been providing her with groceries.

Two weeks ago, I found her busy making a blanket for a batch of eggs.

Steatoda bipunctata, with egg case.

If you look closely at the photo, you can see a dense white ball in the centre of the silk fluff she's making. Those are the eggs.

(The other cobweb spiders, the American house spiders, that I've watched making egg cases cover them in a brownish, rumpled, papery skin. It's impossible to see the spiderlings developing until they break out, some weeks later.) "Brownie's" silk blanket is a nice change.

After a week, the eggs were darker, and spreading out a bit.

Egg mass against the window and blue sky.

Brownie is a sleek, glossy spider, with a fat ball of an abdomen. After she laid her eggs, she was really thin, as thin as a male would be. I fed her more sowbugs, and she bulked up again. And this afternoon, when I went to see how the eggs were developing, there she was, weaving a blanket for another batch of eggs!

I left her to it; I'll pester her with a camera once she's resting.

And I'm wondering: she obviously hasn't seen a male since her last batch of eggs, locked in her box as she is. Does she save sperm for a second batch, or will these not be fertile? Will there actually be spiderlings in that second egg case?

Time will tell.


  1. Anonymous7:04 am

    My money would be on a second batch of spiderlings. A number of arthropods can hold viable sperm for a surprisingly long time, and given the vagaries of breeding circumstances, you'd kind of expect this. It will be interesting to see how this works out!

  2. That should be an interesting observation. What will you do when the first batch of spiderlings hatch? Will you let them go outdoors or feed the horde in the box until the second batch hatches? - Margy

  3. So I'm not the only person who chooses to feed a spider! .... a kindred spirit.

    I look forward to a report of the hatching / hatchings.

  4. Thanks, John. I'm keeping a close watch, and I'll report as the spiderlings emerge. (Or don't.)

    Margy, I'll give them time to settle, then when they start to scatter, they'll have to go out and face the big world outside.

  5. Interestingly, when our snake laid eggs after years of never being with a male, we learned that snakes too can hold sperm for years. Unfortunately we did not end up with any hatchlings.


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