What's That Bug? does not endorse extermination

Unusual web . . .
Hello from the redwoods!
I live in La Honda, which is in the redwoods south of San Francisco. My neighbor called me over this morning to take pictures of these amazing webs she found on the front of her trailer. The are dome-like and we haven’t seen this type of web before. Sorry about the quality of the pictures. I couldn’t get any closer without breaking the anchoring strands of the web. While I was taking pics a “gentleman caller” came to visit, but Miss ran him off by bobbing up and down in her dome. I did manage to get a shot before he was gone. Again, sorry for the quality. Anyway, can you identify this spider for us? Thank you,
Sharon Carthy

Hi Sharon,
The spider photo does not have enough detail to be certain, but indications are that this might be the Marbled Cellar Spider, Holocnemus pluchei, which is pictured on BugGuide. There is no mention of the distinctive web there, but other sites mention the dome web and one research paper by Elizabeth M. Jakob posted online indicates the species was introduced from the Mediterranean to California in the 1970s. We will contact Eric Eaton for verification. Eric provided this correction: “Hi, Daniel: Neat images! The spider is likely the “Sierra dome spider,” Neriene litigiosa. Something in the genus Neriene at any rate. They seem to be locally common where they occur. Keep up the great work! Eric”

Update(11/07/2007)
Found some info on Sierra dome spider here (as well as many other places, but this seemed the most “accessible” to me, the common lay-person): http://biology.unm.edu/biology /pwatson/public_html/pjw_cv.htm No pictures of the dome webs, though. I wonder if the SDS normally builds out in the open like these two did?
Sharon

Hi Sharon,
While there were no photos of the webs, there were photos of the spiders, and they do resemble the spider in your photo. Interesting that the article discusses the energy used during the elaborate mating ritual and that your original observations included the mating ritual.

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