Bug of the Week: Giant Crab Spider

The deserts of Arizona have quite a few unusual arthropods. The sight of some of them can cause visitors to hop right out of their boots. Last night I had one of those in my upstairs bathroom. Here is what I saw:

It is sitting the bottom of the bathroom door, to give you some idea how big it is. What would you do if you saw this?

I have to admit I took these photos in a rush. Not because I was afraid of this giant spider, but because I was afraid our kitten might catch and eat it. I wanted to put it outside quickly in order to save its life.

This is a prime specimen of a giant crab spider, one of the largest spiders around. It can easily get to be 2 inches across. Giant crab spiders don’t build a web, they chase down other arthropods for food at night. Crickets are a favorite snack. They are called crab spiders because their legs extend sideways rather like a crabs.

Can you see the eyes? The big black structures in front are its chelicerae, or jaws. Although it can bite, it is not particularly dangerous. The only potentially harmful spiders we have here are black widows and Arizona brown spiders, a relative of the brown recluse.

I went and got a large glass and a card. I set the opening of the glass over the spider, slid the card under gently so I could lift it from the surface, and then carried the spider outside. It ran away into the night when I let it go. I wished it good luck.

The Arizona-Sonora Desert Museum has more information about the giant crab spider and other desert arthropods.


  1. Karen

    My first reaction? Make it go away!!!

    We try to “rescue” pests in the house or on the screened-in balcony, mostly wasps or lizards or crickets, by the same method you described. I would have really had to “grab a hold” of myself in order to scoop that big spider up!!

  2. Tom Lowe

    I take a small box with a lid, gently brush the creature into it with a whisk broom, close the lid, and take it outside. Works for solpugids, fat scorpions, june bugs, kangaroo rats, mice, etc. I kill bark scorpions on sight if on or in my house with a shoe. Whack!

    Have only had one giant desert centipede in here. It was huge and came in one hot June day to live in a stack of 2×4 that was in the kitchen for a project. It was so fast when it came in that I thought the blur I saw was a mouse. It was in the stack for about two weeks. Had to kill it because I had small kittens. Pounded the stack of 2×4 all over with a hammer and removed each layer. Found it about 12 layers down. Here it is while it was alive and terrorizing the house.


    I let the giant crab spiders do whatever they want. A giant crab spider will clean all the cobweb spiders up in a house, along with the brown widows, and I presume black widows as well. A great help.

    I wonder what giant crab spider vs. adult solpugid would look like. I’d put my money on a berserking solpugid. I think the crab spider would too.

    Crab spiders are rather expressive. Their body language is pronounced and their two eyes on stalks are often very active. They are quite afraid of humans, but usually just try to blend in first rather than running away. Unfortunately that does not work well with humans. If you see one, just leave it be. It will not get into bed with you, and it will clean your house for you–for free.

    Tonight a giant crab spider showed up after several weeks of none here. It killed a brown widow for dinner, but it was near to a pharoah ant entryway and a couple dozen ants took over the kill. In 10 minutes they had it all cut up and carried down into their hole. I poured a blast of Terro down there–don’t want them in here biting my feet this summer. They suck.

    Crab spiders–great guys and girls who clean house better than my tenants do.

  3. Roberta


    You have a lot of wildlife.

  4. Graco

    There was one here in my bed tonight! I was on my phone for a while and when I moved I saw it next to me on my bed. It scared me like ever and now it’s in a jar. I’ll probably put it out in the morning

  5. Steve Starr

    I’m glad I was finally able to identify this huge spider with big black fangs that’s been terrifying me for years. I live in the desert on a ten acre place west of Phoenix AZ and there’s a lot of them. I’m also glad to know they’re not real poisonous but I still wouldn’t want to get bit by the big black fangs they have I’m sure it would hurt.

  6. Russ

    Just found a big dorky crab spider on my Kitchen screen door this hot June morning. One word. Creepy. And another word…Raid. Sorry but I personally will issue certain and swift death unto ALL insects in my house, or in my yard…and especially those in my bedroom or bath. OK…With the exception of praying mantis or a baby cricket…Which I will capture and set free. And while not an insect, I do save Arizona geckos all of the time in my house, with a cup and piece of paper or cardboard…and relocate them back outside. But sorry, spiders anything else…dude…they are total goners if they cross my path.

  7. Roberta

    Keep working on it, Russ. We all can change 🙂

  8. Brenda

    Are they poisen for pets? Will the spider harm them??

  9. Rockybird

    It seems like every summer I find one of these in the house. I try to scoop them into jars to take them outside. There has been one living in my laundry room and I decided to let him be. He’s huge, but far away from my bedroom and he seems to like to hang out there. I’m hoping he will kill any crickets that come in.

    I live by Camelback mtn. I have a huge glass pivot door with a very tiny opening under it, letting it swing. All kinds of things came into the house in the summer under the opening – scorpions, desert centipedes, big spiders, SNAKES (desert night snakes x 2), all kinds of lizards….all I presume for water. I have a sweep now that closes the gap and I don’t see much in the house now (thank goodness), but until it was installed, I put painters tape at the threshold to prevent critters from coming in. One night I found a baby black and orange ground snake stuck on it! Trying to get him off the tape without being bit was a challenge as he kept snapping at me. The desert centipedes cant run on my slick hard floor…I have videos of them running in place like on a treadmill. I would take them outside, because I figure they still serve a purpose in the environment. It was neat seeing all the wildlife, but I prefer it stay outside!

  10. Roberta

    Depending on what kind of pet you have, it is much more likely your pet will harm the spider.

  11. Roberta

    Wow, you have a lot of nature. Thanks for stopping by.

  12. wayne

    just packed one home to montana from az. it lost a leg and i felt sorry for it. am worried about putting it outside in the cold, it lives in my kitchen sink.. guess im ok to let it roam loose in the house…

  13. Roberta

    Yep, it won’t hurt anything (as long as it is a giant crab spider).

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