Common House Spider – Cobweb Weaver

2011 October 29

In an earlier post, I had pictures of a lady beetle that had been caught by a spider in our windowsill, and promised to get to the spider later. Well, now it’s time for the spider:

She’s a common type that builds cobwebs in the corners of windows and doorjams, both inside and outside the house. Going through my files, I find that I also have pictures of what I think is the same species that was photographed on May 30, 2010:

I believe that they are Common House Spiders, Parasteatoda tepidariorum. If you are outside of North
America, then they are American House Spiders. They are another of those “cosmopolitan” species that finds our homes to be congenial, but unlike most of the others, these actually originated in North America rather than Eurasia. This is one of those cases where the common name isn’t very specific, because there are several other kinds of spiders commonly found in houses that are also called “house spiders”, but aren’t particularly related to this one.

Our Common House Spiders build fairly unobtrusive webs, and seem to be living on the insects that are attracted to the windows – ranging from fungus gnats all the way up to largeish beetles. We can usually find one or two somewhere in the house pretty much any time of year. They usually hang upside down in their webs, and judging from the size of their eyes they are practically blind. Their main sensory organ is their web, they feel vibrations in it and then home in on whatever prey they have caught.

When they lay eggs, the females we see generally make two or three egg sacs about the same size as her own abdomen, with a surface that looks kind of like brown paper. These hatch out after a few weeks, making a huge swarm of little spiderlings that then disperse throughout the house. I rarely see the males, which are smaller and evidently spend their time unobtrusively creeping up on females, hoping to be able to mate with them without being eaten. He approaches veerrry carefully, and then, when he gets close enough, he sticks his palpi in her epigyne, and runs off!.

14 Responses
  1. Carole permalink
    October 29, 2011

    Thanks for showing how interesting the common is.

  2. October 30, 2011

    All I can think of when I see these pictures is the female spider asking the male, “Does this make my butt look big?”


  3. October 31, 2011

    Carole: Thanks!

    KT: I don’t think it matters what he says in response to that question. She’s still likely to try to eat him.

  4. October 31, 2011

    No wonder her butt looks big. She’s eating everything in sight!


  5. November 5, 2011

    These are among my favourite spiders. I’ve noticed that immediately after the female has laid her eggs, the abdomen is a lot skinnier; all that bulk is eggs.

    I read this morning that she lays some dud eggs along with the fertile ones, to provide the babies with their first meals.

  6. cassie permalink
    August 15, 2012

    How do u get rid of them

  7. August 15, 2012


    Since they are completely harmless, you don’t need to do anything special to get rid of them. Just vacuum up the visible ones if you find them and their webs unsightly, and you’re done. No need to mess around with poisons. And as a bonus, any of them that are out of sight will help to keep *other* insects down, so you won’t need to poison *them*, either.

  8. Spiderstar permalink
    July 27, 2014

    Don’t vacuum them up! That’s gruesome!

  9. July 28, 2014

    Spiderstar: Well, given my druthers, I personally just leave them alone altogether. But if somebody is really intent on getting rid of them, I don’t think that being poisoned by insecticides is any better for the spider than being vacuumed (and people who are bothered by spiders are generally not too keen on trying to just catch them and toss them outside).

  10. Melissa leys permalink
    August 29, 2015

    I been watching one for weeks now and i notice that she is getting bigger i believe she going to lay her eggs soon i also been taking pictures of her. I think its awesome she is outside of the front door and at night i turn on the light so bugs will get stuck in her web then watch her do her thing when a bug get stuck. Im a person u hates spiders but this one is different.

  11. AKLisbon permalink
    September 23, 2015

    I recently found one behind my bed in a corner with two egg sacs and a very complicated web. How do I carefully get rid of it and the eggs without them exploding?

  12. September 24, 2015

    The egg sacs won’t explode, they won’t do much of anything until the eggs hatch. You can take something like a pencil or a butter knife, sweep around the egg sacs to tear the webbing loose, and just take them outside.

  13. SissyBeans permalink
    October 13, 2018

    They are truly a marvelous creation! The care of their webs is amazing to watch! Every time a pesky line needle gets stuck in our spider’s web, she is out there loosening it up and then the web is beautiful again. And functional. A pure joy to watch!

  14. SissyBeans permalink
    October 13, 2018

    It was supposed to say PINE NEEDLE! NOT LINE NEEDLE! Speaking of pesky things but we are NOT talking about TABLETS!

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