Crab Spider from Cricket Shipment

2010 February 21

We’ve had a tarantula for some time[1], and her primary food is crickets. In the summer, we mostly just catch crickets outside for her to eat, but in the winter that doesn’t work so well and we have to buy them. The only local place to buy crickets is quite a long drive away and has kind of unpredictably irregular business hours, so S_ has decided it will be more convenient to just raise them herself (on which there will probably be more later). So, to get a starting population, she mail-ordered 500 crickets[2]. When they arrived and she transferred them to their new home, she found that there was something else in the box too:

This is a pretty standard-size spider, the body is about 5-6 mm long. Luckily, it was willing to look me in the eyes for a clear face shot, and the eye pattern looks like it is one of the numerous species of crab spider. One of the less crab-like ones, probably one of the “running crab spiders”.

This is exactly the sort of spider that would probably do well in a cage of young crickets. It isn’t big enough to tackle an adult, but would easily be able to handle the hatchlings up through nymphs in the first two molts or so (which are no bigger than the spider). Crab spiders also aren’t much for spinning webs, so it could hang out in sheltered areas where the person raising the crickets woudn’t see it, with no web to betray its presence. The color is not wildly different from the crickets’ color (domesticated feeder crickets are a light brown, not black like most of our wild crickets), so it wouldn’t even stand out to the eye.

The big question in my mind is whether this is a first-generation invader, that got into the cricket cultivation cage when it was just a teensy spiderling and was then living in there in luxury ever since, or whether they have been in the breeder’s cages for generations. The big sticking points for getting really established would be that (a) the initial generation would need to include at least one male and one female, so there would have to be several spiderlings getting in at once; (b) they’d have to avoid having their egg cases either noticed by the cricket breeder during cage cleanings, or eaten by the crickets (who are omnivorous and eat most anything); and (c) the breeder would have to not notice the periodic population explosion of spiders when an egg case hatched out. Overall, I think that a continuing long-term population is probably unlikely, so this was most likely a casual interloper from the fall.

Update on Dec. 14, 2010: The theory that a cricket breeder has an established spider population infesting their rearing cages has just received a pretty substantial boost. First, The Urban Pantheist found a very similar (but larger) spider in a cricket shipment. And then, when I mentioned that it looked a lot like ours here, he found another one on BugGuide that was also found in a shipment of crickets. Twice might be coincidence, but three times (with all three appearing to be the same species) is looking more like a thriving population. The one on BugGuide has been classified as being in the genus Thanatus.

One last picture: the abdomen looks like it is covered by very, very fine hairs. Hairs so fine that they make human hairs look like ropes. If there was some way to use spider hair to make fabric, it would probably be the softest, finest fabric imagineable. And, considering how many spiders would have to be sheared to make it, probably also the most expensive.

[1] We think she’s a Chilean Rosehair tarantula. We adopted her when the previous owners (an office full of graduate students) mostly left town, and the only remaining resident of the office thought she deserved a better home than that. Sam loves her, even though (like most tarantulas) she mostly just sits in one spot and looks menacing. We aren’t sure how old she is, but she’s at least four, which is one of the reasons why we know she isn’t a he (male tarantulas don’t live that long).

[2] The crickets were ordered from a place in Ohio, which is close enough to here that there is a pretty good chance that relatives of this spider are also found in the wild around our house.

5 Responses
  1. February 24, 2010

    I’m interested in hearing about the cricket-raising adventures. If my husband can get past the squeamishness that he’s prone to, I’d like to raise mealworms to feed our birds.

  2. Della3 permalink
    February 25, 2010

    This is not on the above topic, I just had to tell you:
    I happened upon your blog while looking up carpet beetles and got hooked. The pictures and narrative and replies are quite entertaining and interesting. I used to live in the desert. I don’t know why, but there must be 100 times more insects in the desert than in any other environment. Don’t they need more water, or something? I had a desk pushed up to a large picture window. At night I would leave the curtain open. Whenever I looked up I saw an ever-changing assortment of hundreds of bugs, with their various melodramas playing out before my eyes. (A dragonfly biting off the head of a damsel fly – that sort of thing.) And then there’s the joy, (Ha!) of finding a 5 inch long, hideous, solpugid (sun spider) in your bed, and spending the entire night racing around trying to catch the seemingly 100 mph critter and put it outside before you go to bed. Of course, most people are terrified of the non-poisonous creatures and smash them.
    I have only read thru various entries from about the last 18 months, so I don’t know if you have or are planning to dig in the soil and find the thousands of bugs in there as well. What a great project you have undertaken! I don’t think it would ever be possible to run out of new bugs to find, as long as you’re creative on where and how to look.

  3. February 25, 2010

    Joy: I’ll certainly post about the crickets later, probably after they’ve completed a full life cycle so that we can be sure they are actually breeding and not just existing. As far as the mealworms go, S_ raised some of them successfully a few years ago, and we’d probably still be raising them if a dog hadn’t statched the container off the countertop and eaten them.

    Della3: Thanks! We’ve done a bit of looking under rocks so far, but haven’t settled down to sift through the entire top 6 inches of a square foot of soil (although that is in the future plans for the site). As far as insects in the desert, I suspect there are two things making the insects look more common: (1) larger insects have an easier time conserving moisture, so there is an incentive to be bigger in a dry environment; and (2) they don’t have as much vegetation to hide in. There are a lot of bugs in the grass around here that one doesn’t see without poking around, but I bet they’d be painfully obvious on bare, dry soil.

  4. Della3 permalink
    February 26, 2010

    To Tim re: desert bugs
    Good point. The soil is too dry for most to care to bury in, except as shelter from mid-day sun. There’s no ground cover to hide in, so most are just crawling and flying around in the open instead of being confined to so many microhabitats. It’s allll maaakiiing sennnnssse now!

  5. Roberto Granados permalink
    April 28, 2011

    It looks kind of like a Sac spider(?),but again I could be wrong.
    The crab spiders I’ve seen look like,well, crabs.;)

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