Tuesday, July 24, 2007

Spider watching

For the last couple of weeks, I've been pestering a spider I discovered just outside my patio door, poking my camera lens at her, aiming bright lights in her direction, and often shaking her web in the process. At first, I was just trying to get a photo, any photo; she is in a very awkward situation, up in a dark corner where, standing on tiptoe on a chair, I could barely get closer than 6 inches. And stretching like that, my hands shake. But she interested me, so I persisted. I've been taking a couple of photos every day.

She hangs in her web, a tangled mass of threads going every which direction, always upside-down. And usually with her face to the wall. Not until today, after two weeks of trying, had I managed even to see her eyes.

After a few days, she attracted a boyfriend. Ah! Spider sex! I would get a photo! So I've been checking them out several times a day, with no luck, so far. He hangs out in her web, approaching to about 2 inches, but I've never seen him closer. Not yet. (Laurie says I'm intruding on their intimate affairs; I say they don't care. They're not complaining, anyhow.)

An early photo.

Laurie eventually dug out a step-ladder for me. That helps; now I can get a couple of inches away, but only by breaking strands of the web, upon which she heads up, out of range. As soon as I get off my ladder, she comes back to taunt me.

Oh, the trials of a bug watcher!

Anyhow, searching through BugGuide, I found photos of the Western Black Widow that looked very similar, as to body shape and colouring. I tried again to get a look at her underbelly for the hourglass (not getting too close, just in case); she wasn't having any. I posted her photo on the ID Request page, and Eric Eaton relieved my mind; she is an American house spider, Achearanea tepidariorum. Perfectly harmless, he says.

Back to my observation post.

She is a fat spider, with a great mounded abdomen, marked in browns and blacks, with a whitish upside-down vase-shaped mark at the top. The male is tiny and skinny, about 1/4 her size, all legs and quite visible palps.

He hangs around at the edges of the web, sometimes approaching slowly, tentatively. She seems not to notice. I wondered at first if it was because she was still immature, and not interested yet, but one of the websites I consulted says that the webs of immature females are more tightly woven; hers certainly isn't.

The web seems almost too tenuous to catch anything, but last week she had a large brown moth which kept her busy for hours, sucking away at its soft parts. Another time she was eating what looked like a worm; how one would get up there, I have no idea. SpiderPharm tells me that a good part of the success in catching large prey is due to her potent venom. Oh. I'll keep my fingers away.

Yesterday she had a crane fly.

In this second photo, you can see a few of the scanty lines she uses as a trap.

And the male, tiny as he is, had moved down the wall a ways to deal with a moth ten times his size.

male house spiderOn a close-up (click on this for a clear view), you can see the moth scales and the silken lines that bind them.

moth scalesReading up on these spiders, I learn that males and females will inhabit the same web and mate repeatedly. So I guess she won't eat him after the first try. I may get a photo yet.

And then I'll be looking for egg sacs and spiderlings. What fun!

Update: Next post about these spiders: Fresh Laid Eggs!

I found a couple of excellent photos here and here. Somebody has excellent cameras!

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