Does anyone know what spider this is?

Sorry about the crappy photos he was in a jar I put him in earlier when he was crawling on my leg. Some geographic info if it’d help. I’m located in California, in the Bay Area.


Kinda curious.

Zygiella x-notata?

Looks like an orb-weaver, anyway.

I’m not sure. The body looks similar but according to the site, they are a bit larger than the one I found:

(bolding mine)

Does anyone else have a guess? or concur?

Either way, thanks for the reply (and other replies in advance).

Well, how big is it? There’s no reference in the photos. Eleven mm is just under a half inch, is it much bigger than that?

I guess i should have included a better photo for size reference, here’s one with the whole jar so you can see how it compares. It’s unfortunately the best I can do since I already released the spider earlier and left the jar (it wouldn’t come out heh)

Where did you find it? If it is wandering, and an orb weaver (or any other web builder), then you need to be looking at male sizes, not female. Any image which gives an idea of the eye pattern will be really helpful.

I’m going to guess it’s a male Argiope aurantia:

Ugh, third spider identification thread in a row, and this after finding what was hopefully a false black widow in my kid’s umbrella this morning. My scalp itches.

Maybe you found an immature or male one? I’m not much on spiders, but I know that many of the ones that take up residence in my house are all the same species and range from almost too small to see to a leg span of more than an inch. When I’m lazy and don’t vacuum them up, I can watch them get bigger over time.

I don’t think it’s Argiope. Young won’t leave the web site and wander. That’s why it matters where un0wn found it. Had he/she been walking through foliage? I have never heard of Argiope coming inside. I would head into the family Theridiidae - but that’s a huge family. I’m guessing that just from the way it is resting it’s front legs. Best known theridiids are the widow spiders, but there are heaps of smaller ones, especially the greatly varied American house spider:

Ahhh - they’ve changed the genus - just when I have put out a book on spiders with the old name. Drat!!! That is always happening with spiders - such a small proportion are formally classified and they are forever changing them around.

Anyway, this little spider can be very pale and very marked - the males are the size you quote. I have them here (they’ve moved all over the world) and even within a few meters of each other, they are very different in colours. A photo showing the eye pattern, even roughly, would tell - the orb weavers have a very different eye pattern to theridiids.

I’d say this spider was Theridion californicum or a closely related species. The abdomen pattern does superficially resemble some Zygiella, but the carapace shape shows it’s not any orbweaver. Doesn’t resemble an Argiope in the slightest. So Lynne wins the prize for getting it into the right family.

This species has lots of different color forms, as explained in this paper. Some look like this one and some look like this one. They make tiny cobwebs in shrubs such as salal, most often not too far from the coast.

Note for Lynne on name changes: some are well supported and others aren’t. In transferring the “American house spider” from Achaearanea to Parasteatoda, Michael Saaristo in effect said “it’s different because I say so.” I haven’t accepted this change yet, though many others have.

That makes me feel much better. I’d just learned to spell Achaearanea - that took a few years. :slight_smile: They are one of my favourite spiders to observe. Their ability to catch prey so much bigger than themselves, the way the males and females cohabit and mate over weeks - so easy to observe. Great egg sac building, and then heaps of little ones who hang around with Mum for a while. What more could you want in a spider?