Monday, February 2, 2009

The Red backed Jumping Spider

So it was Sunday morning. Glen was reading by the sunny front window, when I heard him say: "Whoa, Janet, get in here quick, there's a jumping spider with a red back!" That was enough to get me into the living room, grabbing the camera as I went.

He was right. This one is called (appropriately enough) the Red backed Jumping Spider, or Phiddipus johnsoni. At least, probably. A quick email/photo sent to Rod Crawford, our local spider expert from the University of Washington Burke museum said it was probably this species, one molt away from adulthood. He thought it might be overwintering here, and advised the best thing we could do for it was to let it find shelter in a cool place to finish out its winter life.

We caught it and took a few bad photos of it, (in the process making the decision it's time to get a macro lens for the camera). The spider withstood our curiosity quite well. Some sources describe this spider as "fearless" and indeed, that was my impression as well.

We have had a special fondness for jumping spiders for many years. My first memorable encounter was one summer. I was sitting in the living room reading, and my deep concentration was disturbed by a house fly, buzzing around me, the lamp, the windows, with that typical fly annoying behavior. I made a mental note to try and catch it to put outside the next time I got up, and went back to my book.

My concentration was again broken when I suddenly heard a very loud, very persistent odd buzzing from that fly. I got up to check it out (naturalists are hugely curious) and found it in the grip of a jumping spider. Apparently the fly had blundered into the window edge near a hunting jumping spider. The spider jumped out, seized the fly, wrapped all 8 legs around the fly and bit it, injecting its venom.

Until the venom took full effect, the spider could only squeeze all of those eight legs around the struggling fly, hang on grimly and wait for paralysis. I watched for about a minute, listening to the frantic buzzing, until finally, the fly went limp. The spider then scuttled off with its unwieldly prey.

Maybe the story is gruesome for some, but not for me. Predators have a place in the world, too. The only true difference between human and spider predators is that we humans hunt our meat in the local supermarket.

So Glen & I happily tolerate jumping spiders in our house, because they do a fine job of keeping other annoying insects under control.

So what happened to our Red backed visitor? It managed to get away, and drop somewhere behind the bookshelf. We hope it takes Rod's advice, and finds a cool, sheltered place to spend the rest of the winter. I look forward to seeing it again.


=Photos and background from Wikipedia
=Check out Rod Crawford's webpage:


  1. Sweet story. I save spiders, too. Thanks for sharing.

    (by the way, I found one of these red-backed jumping spiders in my garden eating a daddy-long-legs, so I was curious what it was, and found your blog)

  2. I saw a black spider with a red butt that moved incredibly fast. His front legs moved as though they were vibrating. It moved so fast that my phone camera could not get focused on it before it was gone.