Spider Identification

Spider Identification

Advice for the Home Gardener from the Help Desk of the
UC Master Gardener Program of Contra Costa County

Client's Request:Visiting the Master Gardener Help Desk at our new relocated offices @ 2380 Bisso Lane in Concord… I found these spiders in my home … Although I know that they aren't normally found in California (e.g., see spiders.ucr.edu/myth.html), I think that they are Brown Recluse Spiders!

yellow Sac Spider
Help Desk Response:  Thank you for bringing your spiders in to the UC Master Gardener Program Help Desk. These are not Brown Recluse Spiders, although I would agree they look somewhat similar. We have identified them as Yellow Sac Spiders,  (Cheiracanthium species). Here is a photo of this spider. The eye pattern is one of the main keys to identification: your specimens have eight eyes whereas the brown recluse only has six.

The link following provides some UC information on spiders, and if you scroll down in the link you will see your spider mentioned.http://ipm.ucanr.edu/PMG/PESTNOTES/pn7442.html 

Yellow sac spiders do sometimes bite if picked up or trapped by clothing, although most people do not experience a bad reaction. You can also find information in the Pest Note on how to manage them. Because spiders are beneficial in the environment, you might consider catching the ones you see and releasing them outside; vacuuming up the spiders and any webs is also quite effective. The bites you have experienced may or may not be caused by the spiders, and I hope that you will not have further problems with this.

If you have any further questions, please feel free to contact us again.

Help Desk of the UC Master Gardener Program of Contra Costa County (SMW)


Note:  UC Master Gardeners Program of Contra Costa's Help Desk is available almost year-round to answer your gardening questions.  Except for a few holidays (e.g., last 2 weeks December), we're open every week, Monday through Thursday for walk-ins from 9:00 am to Noon at 2380 Bisso Lane, Concord, CA 94520. We can also be reached via telephone:  (925) 608-6683, email: ccmg@ucanr.edu, or on the web at http://ccmg.ucanr.edu/Ask_Us/. MGCC Blogs can be found at http://ccmg.ucanr.edu/HortCoCo/ You can also subscribe to the Blog  (//ucanr.edu/blogs/CCMGBlog/)


By Steve I Morse
Author - Contra Costa County Master Gardener