Amy Stewart

Worms in the Heat

Erica asked in the comments if I had any advice about composting with worms during hot summers like the ones she has in Houston. As a native Texan myself, I can appreciate the problem. When I was in college, a non-profit I volunteered for held an annual “Anywhere But Austin in August” fundraiser, so named because truly, a humid Texas summer can be unbearable, for both worms and humans.

The worm most commonly used for composting is Eisenia fetida, sometimes called the red wiggler or the redworm. These critters prefer temperatures in the 60-70 degree range, and really can’t take heat much above 85 degrees. So in a place like Houston, you’ve got a couple of options:

First, consider setting up your bin indoors in a garage or basement. The trick is to make absolutely sure that this room stays cooler than the outdoor temperature. Sometimes a stuffy, non-air-conditioned space like this will actually get warmer than a shady area outdoors. Set up a thermometer in your garage/basement and another one in the coolest, shadiest area of your yard and compare.

If you do think your indoor location will be cool enough, go ahead and set it up there, but keep track of the temperature. On really hot days, think of the worms when you pour yourself a cold drink. Dropping a few ice cubes in the bin will cool things off and keep it from drying out. The contents of the bin should be about as damp as a wrung-out sponge, so just add a few cubes at a time to avoid flooding the bin. And never, never run water through your bin—it will upset the carefully balanced ecosystem in the bin and turn the worms, castings, and compost into a nasty, waterlogged mess. During a really nasty heat wave, you might try leaving the lid off (to prevent the worms from escaping, keep a thick layer of damp shredded newspaper on top and leave a light on), or turning on a fan.

If you don’t have a good indoor location, I’d suggest picking the coolest, shadiest, and breeziest area in your yard. If you plan to build your own bin, consider a wooden bin that is sunk into the ground. On hot days, you might leave the lid off but cover the worms with a thick layer of shredded newspaper or rice straw so they won’t be tempted to go exploring. Worm farmers often use a mister to keep outdoor beds cool and damp in hot weather.

Finally, be careful about the amount of food you add, especially in a large outdoor bin. Fresh food scraps do create their own heat in large quantities. Add food a little at a time or “pre-compost” it in another pile and feed it to the worms once it’s cooled down.

OK, tomorrow we’ll get back to the challenges of air travel with earthworms.

Tales of Airport Security

So I called United Airlines and asked them about taking earthworms with me on the plane. The conversation went something like this:

“Thank you for calling United.”

“Uh…hello…um, I have kind of an odd question about…uh, carry-ons, and…well, sort of…pets.”

(Pause) “OK, what’s your question?”

“Well, here’s the deal. I just finished writing a book about earthworms, and soon I’ll be going on a book tour and I’d like to bring some worms with me. They’d be inside a small Rubbermaid container about the size you’d use for a sandwich. I’ll have the container in my carry-on bag, and I’m just wondering if I’ll have any problems going through security.”

(Even longer pause) “Are these…like…man-eating worms?”

I laughed. OK, this guy was on my side. “No, no, they’re little red wigglers, the kind of worms you’d take fishing. I just didn’t know if the security people would get freaked out and think I was bring some kind of biological agent on board.”

“And these worms are going to stay in the container the whole time, or will you be taking them out on the plane?”

Now I think he was having a little fun with me. “No, I swear, they’ll just stay in my carry-on bag. Do you think it’ll be OK? I’d hate to have to surrender the worms at the checkpoint.”

“I think you’ll be fine. Why don’t you bring a copy of your book to show them—”

“Oh, that’s a great idea.”

“—and maybe even a letter from your publisher or an itinerary or something.”

“Perfect. I think that’ll work.”

“Good luck. Thanks for calling United. Is there any other travel we can help you with to day?”

I considered telling him that my next book would be about boa constrictors or Africanized bees, but I decided I shouldn’t push my luck. “You know, that’s probably enough for today,” I said, and hung up.

Tune in tomorrow, when I ask worm taxonomist Sam James if the worms will be harmed by the baggage X-ray machine…

Worms in the Snow

Sheila Lennon of the Providence Journal asks about keeping worms alive in the snow. If you are an ER fan, you might remember an episode several years ago (Episode 38, “It’s Not Easy Being Greene,” which aired on February 1, 1996, to be exact…I know this because of these crazy guys who are more obsessed with ER than I was in those days) in which a patient came into the ER with her Can-O-Worms and asked Carol to take care of it while she was in the hospital. The worm bin was mistaken for trash and thrown away; by the time Carol found it, a crust of ice had formed around it and she feared the worst. Fortunately, the worms had burrowed into the center of the bin and stayed alive. The patient gave Carol a box of worms so she could get her own colony started.

Sadly, the worms did not go on to have a regular role on ER after that. It’s a shame, really, that worms don’t figure into the plots of more popular TV shows…and I’m not talking about “Fear Factor,” which hardly portrays worms in the positive light they deserve.

So, the lesson to take away from this is that worms can tolerate some freezing temperatures, although their numbers will certainly dwindle when they’re not in their optimal 60-70 degree temperature range. Depending on the severity of the freeze in your area, you might:

Set the bin up in the basement or garage. Really, worms are quite self-contained and not likely to go exploring as long as you keep them happy.

Keep the bin on a sheltered porch and wrap it in an insulating blanket. They can go days or even a few weeks without additional food, so you won’t have to unwrap them very much.
If you have a larger worm operation in mind, build your bin so that it is sunk into the ground (some people use old refrigerators for this) and cover it well with straw, leaves, etc. Shredded newspaper inside the bin makes great insulation and the worms will munch on it, too. Just make sure there’s drainage (like holes covered with fine mesh screens) so the worms don’t get waterlogged.My worms sit on the kitchen porch where they are protected from rain. Here in Humboldt county, the temps reach freezing a couple dozen times over the winter, and once in a great while it’ll get down in the twenties.

My experience has been that worms are, overall, content with their lot in life. They are peaceful, docile, focused on the task at hand (so to speak), and not given to complaining about the cold.


The holidays have been good to the worms. They are still working on Thanksgiving dinner: Brussels sprout trimmings, potato peels, squash rind, and coffee, coffee, coffee. We had eight people in the house for two days and I think we went through an entire pound of coffee. The caffeine doesn’t seem to affect the worms, although I wonder if the acidity of the grounds is starting to throw off the pH in the bin. They can’t tolerate an acid environment, and it seems that as the pH drops, the ants move in. Although the ants don’t seem to bother the worms, it just gets to be a bit of a circus in the bins. I’ve already got sowbugs and a miniature white cousin to the earthworm called a potworm inhabiting the bin. And there are millions of microscopic creatures teeming around in the rotting mass of food, too: bacteria, nematodes, fungi, protozoa—all eating the food and becoming food for the worms. It’s a real miniature zoo on the back porch.

So I throw in some eggshells to help combat the acidity. The worms can’t eat the shells, but they crumble up nicely and eventually they’ll go into the soil along with the castings.
Speaking of worms and coffee, an AP story this morning reports on the effects of intoxication on worms. They’re speaking in this case about a nematode—a microscopic roundworm named C. elegans. When you read about worms in the news, they’re almost always talking about C. elegans. It’s the lab rat of the worm world. Those worms on the space shuttle were C. elegans, too. I tell you, the humble nightcrawler and the red wiggler almost never get their due.

Why Worms?

I suppose I should explain how I got into worms in the first place. I planted my first garden in Santa Cruz, California about eight years ago (and wrote a book about it called From the Ground Up: The Story of a First Garden), and it wasn’t long before I was buying every garden accessory and toy I could get my hands on. I had a serious Saturday-morning nursery habit. Most of my paycheck went to plants, rakes, shovels, and bags of compost. I was in deep.

One morning the nursery had a display of worm bins for sale. The bins, which are called Can-O-Worms, consist of three round stacking trays with small holes in the bottom. You stack the trays on a sturdy plastic base, introduce worms into the bottom level, and eventually they work their way through each level, eating kitchen scraps as they go. Once they’ve massed in the top tray, the bottom tray is usually full of castings—worm manure—that is ready to go into the garden. You empty the bottom tray, make it the new top tray, and keep going. The worms never leave the bin; they just move through each tray in an endless cycle of eating, reproducing, and—well, shitting.

It’s hard to say why the worms appealed to me so much, exactly. Part of it is that I wanted that worm shit, which is the finest cuisine you could feed a plant and extraordinarily expensive if you buy it retail. Part of it was that I liked the gear. A worm bin is hip, in an organic, northern California way. And part of it is just that a colony of anything is fascinating to watch. Ants, bees, worms—they all have curious customs, unfamiliar ways of life, and I thought I’d find them entertaining.

Now I have thousands of worms living in two bins on my back porch, and they’ve kept me entertained for years. They are good pets, loyal and hardworking, and they earn their keep. I wrote this book—the new one, The Earth Moved—for a lot of reasons, but one of them was that I wanted to pay tribute to the inveterate invertebrates that live their lives outside my kitchen door, devouring my coffee grounds and my morning paper, leaving their rich black castings behind.

Crazy Worm

It rained all night, and that can only mean one thing: worms on the sidewalk. Oddly, no one knows exactly why worms wriggle onto the pavement, a place of near-certain death, on rainy mornings. The best guess is that they can sense a change in barometric pressure or humidity and, fearing a flood, they stage a walkout. Earthworms breathe through specialized cells in their skin that exchange carbon dioxide for oxygen. They like dampness, but they won’t live long underwater.

Worm farmers live in fear of a walkout, a kind of group-think behavior in which thousands of worms rise from their bedding at once and mass on the pavement, or even the walls of a shed, which makes it impossible to round them up and herd them back to their home. On a rainy night, a worm farmer will leave floodlights shining on the worms all night, hoping that their dread of light will overcome their fear of floods.

After a rain like the one we had last night, I make sure that my morning walk takes me past a house down the street that has a fine colony of Amynthas corticis, an Asian worm that’s sometimes called a snake worm or a crazy worm. These worms are about six inches long and so excitable that they will lash around and try to jump right out of your hand. I like to collect these worms and add them to my own garden, just to increase the overall diversity of the subterranean population. I used to deposit them all in a rich patch of earth near my back door, where I hoped they would find each other and mate. Then I realized that these worms are parthenogenetic—they reproduce without sex—so now I scatter them all over the garden and hope they’ll clone themselves. Another strange fact about this worm: it will shed its tail to escape a predator, much the way a lizard would. I’ve never seen it do this myself.

So I always find one or two snake worms on the sidewalk near this particular house after a rain, and sure enough, there was one there today. It’s a dark worm, more brownish-black than pink or red. I picked it up and cupped it between my palms. It whipped against my skin in protest, but I carried it home, and when I reached my garden, I opened my hands and it leapt to the earth.

The Book of Worms.

It’s a strange feeling to open the door on a rainy Monday afternoon, when you are still in your pajamas for reasons you cannot explain, and face a UPS man who holds in his hands a package containing the book you just spent three years writing.

And when you open that package and find a picture of one of your very own earthworms on the cover, it gets even stranger.

This particular worm doesn’t have a name or a gender. It lacks hearing and sight. While I can’t prove it, I do assume that it has no memory of the afternoon it spent in my attic while I photographed it, Richard Avedon-style, against a plain white backdrop. I had seen the early draft of the cover from my publisher and I felt strongly that the book must have a picture of an earthworm on it somewhere. So I went outside, dug this one up, and hollered, “You’re gonna be a star!” Then I carried it upstairs for a photography session.

It’s a fine worm. A nightcrawler, Latin name Lumbricus terrestris, the very same worm that Charles Darwin wrote about in his last book, The Formation of Vegetable Mould, Through the Action of Worms, With Observations on Their Habits. This quirky little book is largely forgotten today, but during his lifetime it was one of his bestsellers, probably because he showed such affection for his subject. It was Darwin’s book that inspired me to write a book about earthworms in the first place.

Most writers will tell you that by the time their book has been published, they have forgotten all about it and moved on to something else. But that’s not true of me and my worms. Earthworms are a part of my life. I suppose they always will be.

I started this blog because I knew that things would happen on my book tour that would be stranger than fiction. After all, I’m traveling with worms. It’s bound to get weird.
But that’s not all. I know I’m not the only one who is fascinated by this blind, deaf, and spineless creature that lives underground and swallows dirt for a living. So welcome, worm lovers of the world. This is your home.