Sunday, May 16, 2010

A beetle in the bathtub

The spider beetle, Gibbium aequinoctiale.

About once a year, first thing in the morning, I find one of these in my bathtub.

It stands out against the white background. It’s dark red, about one eighth of an inch long, and has a bulbous body, tiny head, and long expressive antennae the same color as its three pairs of legs. It sits in the tub, unexplained. If I touch it, it curls up and plays dead.

It’s a beetle, although it doesn’t fit most people’s mental image of a beetle. There are more than 350,000 kinds of beetles, and they come in lots of shapes and colors. This one looks a little bit like a spider because of its round body, and the long antennae can be easily mistaken for another pair of legs, which would add up to eight -- the number of legs on a spider.

Spider beetles also get misidentified as bedbugs pretty often because of they are the same color. Everyone is always happy to find out they are wrong about that!  Bedbugs are flat, not globe shaped.

Scientists usually report that spider beetles eat “a variety of dead materials of animal and plant origin,” including flour, old wood, seeds, wool, feathers, leather, and fabrics. Spider beetle can be pests of stored food products, and actually will eat almost anything dry, including more appealing sounding things like breakfast cereal, figs, instant soup mix, rye bread, spices, and chocolate powder. 

Hmmm. None of these things are ever found in my bathtub…so why do I always only ever find spider beetles there?

They forage at night, and most of them scurry back to their day resting places before I rise. But about once a year, an errant beetle making its nightly rounds discovers the dark bathroom. They are attracted to moisture. Exploring. Climbing. Oh no! It falls into the tub! It can’t get out! Morning comes, and behold – there is a beetle in the bathtub.

There is more information about spider beetles in my book, A Field Guide to Urban Wildlife of North America, which will be published by Stackpole Books in spring 2011. 


  1. I CAN NOT believe I found this blog.
    I have two sitting in a plastic container on my sink. They WERE in the tub.

    I thought they were either ticks or bedbugs.

    I will not freak out now.

    1. Great that it was just spider beetles and not ticks or bedbugs! Spider beetle identification is often accompanied by sighs of relief. I think they are actually sort of cute. :)

  2. Great blog, too.
    I walk Central Park a lot, too.
    It keeps me sane.

    BTW: we couldn't kill the beetle, so we put it outside.

  3. I'm so glad I found this for two reasons. One, I just found one of these on my bed and wanted to know what it was, and two, I happen to have just purchased a membership to your museum. Yay.

    1. It's good to know what they are since they show up in the home every now and then. Congratulations on your membership and welcome -- I'm sure you will love it!

  4. I keep finding these crawling up the wall of my bathroom and I just found 2 dead ones in my light fixture. Was worried they were bed bugs or ticks, too. Thanks!