Running Crab Spider From California

Hi there-

I took a picture of this bug that hitched a ride to work on my car 10 years ago, and I’ve never been able to positively identify it beyond the fact that it’s some kind of crab spider. Including leg span, it was no bigger than a silver dollar. My camera’s white balance darkened it – in person it looked almost uniformly white, and so furry that it looked velvety (maybe an optical illusion?). The photo was taken in the CA Bay Area (Emeryville, but the critter probably boarded in northeast San Francisco) in the summer.

Very interested to know your thoughts!

With many thanks for your time,


Dear Rachel,

We are so thrilled to be able to solve your 10 year old mystery.

We agree that this is “some kind of crab spider” but it is not in the Crab Spider family Thomisidae.  Rather it is a Running Crab Spider in the family Philodromidae.  Based on your location, we are relatively confident that this is Philodromus californicus which we found pictured on BugGuide (link     According to BugGuide (link, the range is “Northern Mexico and California to British Columbia, eastward to New Mexico and Colorado” 


  • Bugman

    Bugman aka Daniel Marlos has been identifying bugs since 1999. is his passion project and it has helped millions of readers identify the bug that has been bugging them for over two decades. You can reach out to him through our Contact Page.

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