Cellar Spider, and Spider Cages

2008 November 29

These spiders tend to hang out in corners in our basement, just like everybody else’s basement.

They are “cellar spiders”[1], in the family Pholcidae. These in particular are probably Pholcus phalangioides, which is another of those cosmopolitan species that humans have carried all over the world. They are perfectly harmless, of course, but a lot of people get antsy about them because they are the sorts of spiders you are likely to find building webs under the bed. So, when a kid wakes up with some sort of “bites”, and the worried parent looks around the bed and finds a bunch of these hanging around, they are likely to get blamed for it, but honest, they didn’t do it (and, in fact, are quite likely to be catching and eating the fleas, bedbugs, or mosquitos that did do it).

They spin the classic “cobweb” type of web, a loose, 3-dimensional structure that is practically invisible until the spider dies or otherwise abandons them, at which point they get all covered with dust and become easy to see.

Getting good pictures of the spiders is proving to be a bit of a problem for me, because they tend to hang out in dark corners, and are kind of fragile, which makes it hard to catch them and get them into decent light. The picture above was taken of a spider behind a cabinet in the kitchen back in May, and the light was awful (I had to brighten up the image a lot with ImageJ, which threw the color off a bit). I had to hand-hold the camera in bad light, and it came out kind of blurry. Then, when I went back to try again, it had moved on.

So, yesterday I finally got around to catching another one to try again. She turned out to be only really happy if she was hanging upside down from her cobwebs, so attempting to flip her over and position her under the camera made her exceedingly unhappy. So far, the best approach I’ve come up with is to get the spider hanging on some structure that I can move around, prop it up in a suitable position, then either slide the camera underneath and take pictures from below, or try to come in from the side. Here is a picture of her from below:

Here the spider is backlit, so we can see that she[2] is not only pale, but the legs and cephalothorax[3] are practically transparent. This makes her pretty unobtrusive, so it is all the more likely that her prey will bumble into the web without noticing anything amiss until it is Far Too Late.

I was eventually able to get her hanging inside a jar that was laying on its side, and persuaded her to face me. This finally gave a halfway decent shot of her face, which clearly showed the eyes.

The eyes are arranged differently from the spiders I’ve shown up to now, she has two clusters of three eyes, and between them one cluster of two eyes, for a total of eight. This is very different from the two evenly-spaced rows that one sees in, say, crab spiders, and is very characteristic for pholcid spiders.

Now is probably a good time to talk about how we sometimes keep spiders as pets. S_ came up with the idea of cutting circle of window screen to go into the rings used to put lids on mason jars for canning:

This is handy, because little half-pint mason jars make great containers for catching spiders – large enough to get them into, but small enough that they are easy to handle. Once the spider is caught, we put in either a cotton ball or a small piece of folded paper towel soaked with water, and put on the screen lid.

The reason for using window screen, instead of the traditional “poke some holes in the lid”, is because poking holes in the lid never works. If holes in the lid are small enough to keep the spider from escaping, they are also small enough that there is not enough air exchange. When I was a kid, we would occasionally try to keep insects in a jar with holes in the lid, and they would always accumulate moisture inside until whatever was there would drown in it. It was nasty. That never happens with the screen tops, there is excellent ventilation and everything we keep in them, from spiders to monarch caterpillars, tends to thrive.

So, now, to keep a spider, we just catch it [4] and pop in some small prey item (I usually use flies, because they are available) about once every two or three days, and everything’s good. Just remoisten the cotton/paper towel every week or so[5], keep feeding it, and she’ll be good for a long time. We’ve kept spiders as long as three months this way, we usually end up letting them go again before they actually die.

[1] Some would call it a “Daddy Longlegs”, but I won’t, for reasons that I have gone into before

[2] I say “she” because she’s pretty plump. Male spiders in general tend to be smaller than the females, and the pictures I’ve seen of pholcid spiders shows the males to be these skinny little guys.

[3] The cephalothorax is the front part of the body, with the rear part being the abdomen. Unlike insects, spiders don’t have a distinct head, it is kind of merged with the part of the body that the legs come out of.

[4] There are a couple of ways to catch a spider in a jar without actually having to touch the spider, which is good because spiders are very fragile, and if you try grabbing them they often lose legs. If the spider is on the wall or the floor, take your jar and a playing card. Put the jar over the spider, then slide the playing card over the mouth. Then, flip over the jar+card, tap the card to knock the spider into the bottom of the jar, and voila! If the spider is in a web (like this one was), manuver the jar underneath the spider, then use a pencil point to tap above the spider. Generally, she’ll let go of the web and drop straight down, with luck going right into the jar. Again, voila!

[5] A good way to do the remoistening is to take a drinking straw, put it in a tall glass full of water, put your finger over the top end so the water doesn’t run out, and press the end against the cotton/paper towel wad. Then take your finger off the other end, and watch it soak up the water.

14 Responses
  1. November 30, 2008

    Outstanding! I’m not sure I can convince my daughter that these little dudes and dudettes are beneficial, though.

    I love the anecdotes you add about overcoming the difficulties photographing these little beasties.

  2. Margaret B permalink
    December 8, 2008

    Are these the guys/gals that are very entertaining when frightened? I once lived in a house with an oddly-shaped-stone wall, and it accumulated spiders. I mentioned them to a teacher (who I’m told is a renowned authority) and he suggested I scare scare them — blow on the web.

    They put on quite a show — bouncing the web, moving a lot. Not sure if they wanted to appear larger to their predator, or if they wanted to become invisible.

  3. December 8, 2008

    Yep, that’s them. It made it a bit hard to drop it into the jar, luckily the jar had a wide enough mouth to catch her.

  4. Ryan permalink
    June 8, 2010

    Well I just flushed a big one – spider that is. She had a big butt that I assumed was chock-full of babies. I live in a finished basement, so I have to get rid of them. Otherwise they’ll crawl up my nose and sit in my earholes when I sleep.

  5. June 14, 2010

    are grand daddy long legs posinus or deadly

  6. June 14, 2010

    Nope. Even assuming that a cellar spider like this one did bite you (which is pretty unlikely), there’s no indication that their venom is anything special, and you probably woudn’t notice it any more than a mosquito bite. And if you mean the other main kind of “grand daddy long legs” (Harvestmen), they don’t even have venom.

  7. Zainab al-Ashkar permalink
    September 25, 2010

    Hey I just happened onto this site and noticed this article and I have to say that it softened my attitudes towards Pholcids- a bit. For some reason, I have been able to tolerate most spiders, I even think some species are kind of cute, like the brown Steatoda house spider, but I never liked Pholcids. Just the sight of a full-grown one was enough to send me into a fit of panic. In fact 2 months ago I was hospitalized for this very thing…I was surprised by a two-incher in my kitchen cabinet and I lost my breath and couldn’t catch it back. My husband thankfully was nearby. It’s just this particular kind that I fear more than the devil himself. I can’t for the life of me figure out why, but I need to because we’re now being overrun by them. My next door neighbors have hundreds in their place. We were invited to dinner one night and I counted over 300 just in the living room. There were almost that many in the kitchen. Needless to say my husband and I quickly found an “emergency” we had to tend to.

  8. John Hardin permalink
    November 18, 2010

    Ode To A Daddy Long-Legs Spider

    While Pholcus phalangiodes
    May incite anxieties
    We’ve nothing at all to fear
    From this little spider here
    In her web up in the corner
    There’s no reason we should scorn her
    She’s been with us since we were apes
    And caught more flies than sticky tapes
    We wreck her home each time we dust
    But she’s never harmed a one of us
    For long ago she realized
    Our homes are warm and we draw flies

  9. November 18, 2010

    Nice poem, thanks! I especially like the last two lines.

  10. Roberto Granados permalink
    April 26, 2011

    I really like your website,and I find a lot of useful information in it.
    Where I live,in Northern California,we have another species of cellar
    spider,the Marbled cellar spider(Holocnemus pluchei).They look pretty much
    like Pholcus phalangioides,except they have pretty brown patterns on the

    About shooting photos of them:
    I encountered the same lighting problem,but figured out an easy way to solve it.
    You can use a higher exposure or contrast,but for very dark areas,you can shine a
    desk lamp on the spider and change the white balance to “incandescent”.
    That should solve the problem.

  11. April 27, 2011

    Thanks, Roberto. Since taking these pictures, I’ve upgraded my camera considerably, so it’s probably time to re-shoot these particular spiders. In particular, I’ve got a flash solution that really takes care of most of my lighting issues.

  12. macy jamal permalink
    June 3, 2011

    these are actually the most poisonous spiders in the world, but cant bite humans because their fangs are to small

  13. June 3, 2011

    macy jamal: I’m afraid you’ve been taken in by a myth. See this site, for example:


    Basically, there is no record of anyone ever actually testing this spider’s venom for toxicity. So, for the people claiming it is highly toxic – how would they know?

  14. November 22, 2020

    These spiders tend to hang out in corners in our basement, just like everybody elses basement.

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