I found this spider on my balcony in Sunnyvale, CA. It sat in a irregular net. The body was approx. 6mm long. Which species does it belong to?

Spider in its web under a table on my balcony The same spider on a newspaper.


1 Answer 1


That's a Western Black Widow subadult female. The banded legs, with dark 'knees' and lighter brown intervals, become all black as the spider matures, just as the bands on the body disappear as it becomes all black.

Below is a slightly older one, where the center stripe is beginning to turn red. Your first clue is the irregular web, characteristic of the Theridiid cobweb spiders. The second clue is the robust body and legs, with especially long first and last pairs. The key field mark, if you had seen the underside, is the red or orange hourglass. It is clearly not any kind of orbweaver, simply from the web; and none of the several sorts of Argiope look anything like this spider.

Be aware that this spider can give quite a potent bite (although they often don't, preferring to hide, and not biting unless endangered). Like the other Black Widows, they are best not handled, just in case.

https://bugguide.net/node/view/1458045/bgimageenter image description here


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