Is this a widow? - Steatoda grossa

I'd say definately a female b

I'd say definately a female black widow and due to your location most likely a western widow, Latrodectus hesperus. But a look at the underside would be the way to tell the species. Looking at size probably a gravid one too.

… Tim Perry, 7 February, 2006 - 1:37pm

Thanks for the feedback!

She was understandably a little ticked off when I caught her in a plastic jar to relocate her. Didn't see the belly clearly but I think there were hints of red.
Good thing I found and moved her before she dropped her offspring.

… Michael, 7 February, 2006 - 1:42pm

A fat one.

At that size, it sure seems like a black widow. The red spots on the underside should tell you for sure. If it doesn't have the red spots it's likely Steatoda grossa, but this would be quite a large grossa.

… Lynette Schimming, 7 February, 2006 - 6:27am

Lynette Nails It:-)

This is indeed a female of Steatoda grossa. You can barely make out the faint row of pale spots down the middle of the abdomen. The overall purplish-brown color is relatively diagnostic as well. This species can get quite large for the genus. Often, the markings on females are very indistinct like this.

… Eric R. Eaton, 7 February, 2006 - 2:39pm

What a relief!

My wife was starting to develop a garage-phobia since I told her about my catch last night.
I assume the Steatoda grossa is harmless as opposed to a real widow?

… Michael, 7 February, 2006 - 2:43pm

Not Quite

The effects are less severe, but similar- Black Widow Lite. Not a spider to trifle with, but far from life-threatening.

Chances are, though, that you have Black Widows, too (most homes in Southern California do)- but you'll probably never see them . It's just a good idea not to stick bare fingers in dark places where something might hide. With that precaution, you should have no problem.

… Chuck Entz, 8 February, 2006 - 7:32am

steatoda grossas compete with and prey upon black widows

If black widows worry you, consider keeping the steatoda grossas around.

I currently have a specimen in a clear cup that is about 13-14 mm long that I recovered in the garage a few days ago, and that's as big a s. grossa that I've seen. I gave her a layer of pelletized horse bedding as substrate, and she's constructed a little cobweb. If yours was 15-20 mm, you must have had plenty of critters for her to eat in your garage.

… dumbunny, 5 April, 2007 - 2:57am