The Short Story of the California Red-Backed Jumping Spider

Phidippus johnsoni – Red-Backed Jumping Spider

Edited to add (7/11/11): Thanks to a couple of knowledgeable and generous commenters (below) the positive ID on this jumping spider is “Ms.” :)

I found this little Mr. (or Ms.) on the kitchen ceiling a few days ago. Before I could grab my telephoto to see precisely what type of venomous spider might be parachuting onto my head during dinner, he (or she) disappeared.

Today, I saw the black splotch in my peripheral vision again. But I couldn’t get much of a shot in the available light without my tripod (which I routinely forget in the car).

Blur of a Red-Backed Jumping Spider

Blur of Red-Backed Jumping Spider - Phidippus johnsoni - ©ingrid

I could obviously make out the red stripes on the spider’s back. But I don’t know enough about spiders to make a firm ID. Google turned up references to the most dangerous spider in Australia, the Redback . . . a species I could have dismissed had there not been one alleged sighting in Texas.

So, I figured that absent any species consensus, I’d have to find a way to get the guy with the redback (but not necessarily a Redback) outside without risking interaction. Spiders get the benefit of the doubt in this household.

When he climbed on a painting, I seized the moment. I grabbed the frame and swung it outside the door, just as my spider friend plummeted outdoors on a sheen of silk.

The anthropomorphic interpretation of this spider’s expression: “What in the hell was that about?”

I positively identified this guy after the fact. Had I known my California Arachnidae, I’d have known he (or she) was a Red-Backed Jumping Spider (Phidippus johnsoni), common in California. And I might have known the preferred habitat is tucked under something on the ground, not on a leaf — where he landed.

I would have understood that although it has some venom, its bite is not fatal. An encounter would generally only happen if the spider felt threatened, and then, a spider-inflicted injury would render minor swelling and pain. (Being catapulted out the door on the frame of a painting probably constitutes being “threatened.” So if I’d been bitten, whose fault would that have been?)

A person who raises Red-Backed Jumping spiders commented on my Flickr photo, attesting to their relatively docile nature. (Lots more great Red-Backed Spider pics at their Flickr site: The Green Thumb/Spider Pics.)

Here was my last vision of the eight-legged, dancing upon its gossamer silks before trundling off down the tree limb.


Gossamer (silk) of the Red-Backed Jumping Spider - ©ingrid


  1. Kat says

    If it has a black stripe in the center of the red, it’s a female. If it’s just red, it’s a male. I found one at school (at first I thought it was a ladybug) and just had to figure out what it was. (;

  2. Chester Drawers says

    My son is recovering from a spider bite, allegedly from a ‘latrodectus mactans’ (black widow). So I am on the lookout for squishing anything with eight legs, black, and moves in our house. I got one this morning with a combination of three spray cans of black flag and a swatter. What was left of him stuck in the swatter seems to indicate that he was innocent an possibly really a kind of ally. Sorry nature, but better to be safe than sorrry here in the southern California desert, home to black widows the size of silver dollars and birds of prey the size of buicks.

  3. says

    Barry, you can find jumping spiders around the world, and — I had to look it up to make sure — definitely in Louisiana. But I’m not sure which type of jumping spider you’d see there.

    @ Kat & C.D., thanks and sorry for the delayed acknowledgement.

  4. says

    Hi, Barry, thanks for the clarification. I don’t know for sure and everything I’ve read so far claims the range for Phidippus johnsoni is “western North America from the Rocky Mountains to the Pacific Coast.” I’ll see if I can find out, or perhaps someone with a bit more information on this species will happen upon the post.

  5. says

    My room is currently infested with these things… I immediately killed the first one I saw, thinking it was a black widow. But now I just shew them out a window. Their behavior is quite timid and non-threatening.

    • Evan says

      I thought the same thing when I encountered one the other day. My cat was trying to play with it, and my first instinct was it was a black widow due to the black and red. However, widows have the red on their underside (abdomen), and their legs are more elongated. Black widows will seldom be seen during the day either, they like to come out at night.

      Jumping spiders also are indeed very timid and unlike most spiders, will react to you and get scared and hide just by seeing you.

      I used to have a ton of them at my old house. They were black and white with bright, green eyes. Pretty cool.

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