How to Get Rid of and Prevent Clothes Moths

The last of the moth-infected stuff from the studio is sitting in my kitchen, waiting to be cycled through the oven. Yeah, you heard me. I’m still at this. A week later. I have two bolts of silk, an alpaca fleece, and a couple of bags of llama fiber left. I should be done with that part today. Then I have to go through every closet and storage box in the house and deal with the clothes.

The part that is really killing me, though, is the sheer amount of plastic this requires. I was planning on moving my stash out of plastic over the coming years, and into fabric-lined lidded baskets. Well, no more my friends. I am not bloody doing this twice, I can tell you that right now. So everything is being processed to kill the moths, then bagged in 4mm clear plastic bags and put into plastic totes. The totes have already been washed with hot soapy water, and then sprayed with moth repelling essential oils while still hot. Plastic, being porous, sucks up the oils and stays smelly pretty much forever. Then I lob two moth repelling sachets into the tote, spritz it with diatomaceous earth, and then tape the whole thing shut with packing tape. I like to wear a belt and suspenders on my overalls in such situations.

The theory behind all of this? You may want to sit down for this part, because I have (of necessity) become something of an expert at killing these horrid white squirmy monsters.

Exterminate the Beasties

First, you have to get the dirty rotten so-and-sos to stop chewing holes in your things.  You do that by killing them. You can freeze them, which kills the adults and the larvae, but it does not kill the eggs. You have to freeze your stuff for a minimum of three days, thaw it, let the eggs hatch, and freeze it again. As the hatching takes four to ten days in warm weather, you should repeat the freezing in about two weeks to make sure you got everything. Given the absolute WALL of plastic totes behind me, and the tiny amount of available freezer space not taken up by food, that method would have taken me months. So I opted for heat instead. Thirty minutes at temperatures over 120 degrees F (49 degrees C) will kill all stages of clothing moth; egg, larvae, and adult alike. Sign me up.

So I set my oven to 200 degrees F (93 degrees C) and ran everything through for thirty minutes. I want to make sure nothing survives. Will the temperature hurt the fiber? Nope. Know how I know? When you iron wool and silk, you do so at about 300 degrees F. In fact, any temperature under 392 degrees F is perfectly safe. Yeah, I looked it up. There is one caveat, and on this one I got lucky. You cannot do this to a raw sheep fleece. The lanolin melts at those temperatures (anything above 100 degrees F), and when allowed to cool, it chemically changes and becomes almost impossible to remove. Once the wool has been scoured it has already had most of the lanolin removed, and all chemical changes have already been wrought, so clean wool and yarn are perfectly safe to bake.  My luck? I had only one raw sheep fleece, and it was so infested it went straight into the trash. The alpaca and llama fiber have no lanolin, and are thus completely safe to bake, even raw (which really just means sandy).

A word on other methods of extermination. There are several, and I’d like to take a moment to discuss why you should not do them, if at all possible. First, there is dry ice fumigation. You do this by enclosing the material in air tight plastic, putting a small piece of dry ice in the bottom, and sealing it shut. You leave it for at least three days. This kills all stages of moth, but dry ice is difficult to get in many places, and you run the risk of frostbite. This would be an excellent method, however, for saving a piece of wool or horsehair stuffed furniture, if you could not take it outside and freeze it.

You can dry-clean your things, which kills everything, and removes any attractive staining. Dry-cleaning chemicals, however, are notoriously toxic, and if you have a large number of things to save, it could be quite costly. The same goes for chemicals used by professional exterminators, though permethrin (made from orange peels) is safe enough for people, as long as you have no cats or fish in the house. For them, it is extraordinarily toxic. We have five cats, so this one is absolutely off the list for us.

Prevention

So, once the moths are dead, how do you keep them from re-infesting your things? The problem with these guys is that they don’t just infest your clothes or yarn. They infest your house, too. Which means that unless you take steps, you’ll be right back where you started. Understanding how to prevent a moth infestation (which would have been so much smarter of me in the FIRST PLACE) starts with understanding the life-cycle of the clothing moth. This is going to get a little nuts.

The whole thing starts with a pregnant female moth. She’s looking for a place to lay her eggs, and she finds it by following her nose. She is afraid of the light, and not a very good flyer. This means that she’ll hide quite well, and you will likely not ever see her. If you do, she will be more likely to run away from you than fly. She will lay anywhere between 30 and 200 eggs in any animal hair (wool, alpaca, cashmere, angora, fur, discarded human hair, etc.), protein fiber (silk), or in fact, in grain. Damp, stained, or smelly things are vastly preferred, because the caterpillars do not drink, and must get their moisture from their food. With that said, live caterpillars have been found in bags of salt. No kidding. I told you this was ridiculous.

The eggs take four to ten days to hatch. Once they do, they start eating whatever they were laid in. Often, it is your favorite cashmere sweater. For me, it was my fiber stash. As they feed, they spin a webbing mat, which they hide under. This mat typically contains dye and fiber from whatever they are eating, so detecting them can be almost impossible. Usually the first symptom of an infestation is moth holes in your best wool suit. They will continue to feed at a rate determined by temperature and humidity. The colder and dryer it is, the longer it takes. Larvae will hatch and grow at temperatures ranging from 50 degrees F (10 degrees C) to 91 degrees F (33 degrees C), with ideal conditions being about 75 degrees F (24 degrees C) and 70-75% relative humidity. This stage can take as little as a month… or as long as two years. Yeah, I kinda wanted to cry at that one.

Once they have gorged themselves on your hand knit socks, they spin themselves cocoons, and become pupae. Now here’s the tricky part. They often actually crawl away from their food source in order to do this. This means that they can crawl off your woolens and onto something that is cotton, viscose, or synthetic. Thus it is EXTREMELY important to wash everything in the infected area. Do not skimp out here, or you may be sorry. Once they are cocooned, they will spend 10 to 50 days transforming into adults.

After the adults emerge from their cocoons, it is important to understand that they do not, and in fact cannot eat. It is only the larvae who do the damage. The adults do not even have working mouth parts. An adult female clothing moth will mate, and lay her eggs, and she has only about 15 days in which to do this. Males will live a bit longer (figures, right?); about 30 days. Males find the females by using their nose as well. The females give off a very specific pheromone. We’ll get back to that later.

So how does all of this help us prevent infestation, or re-infestation? Let’s start with our adult female moth, shall we? After all, no eggs mean no hungry hungry caterpillars. The first, most excellent prevention method is as simple as a barrier. If the moths cannot get to the woolens, they cannot lay their eggs in them. Makes sense, right? Well, clothing moths are TINY. So the only way to be completely sure is to encase everything in air-tight plastic. I know, I know, it makes me crazy too. Just bite the bullet and do it. If you really can’t stomach it, or if (heaven forbid) you actually want to use some of the things you own, there are some different measures you can take.

In addition to the barrier method, you can employ a substance called diatomaceous earth. It is the fossilized remains of microscopic sea creatures, and comes as a powder. For any animal without an exoskeleton it is completely harmless (caveat – don’t breathe in a ton of it, it is still a powder, after all). But to creatures who carry their bones on the outside, it is quite deadly. We have used it for years to keep the house free of fleas. It gets in between the plates of the exoskeleton and rubs, causing tiny scratches. The insects actually die of dehydration, so the one thing to remember is that it absolutely does not work once it gets wet. As soon as it is dry again, however, you’re back in business. It is a physiological death mechanism, and thus there is no adapting to it. In addition, there is a food grade variety (which is the only one you should be buying) that has no additives. It is designed to be added to grain products, such as flour, to keep the weevils out. If you eat grain, you are already eating diatomaceous earth.

One of the things about re-learning an older way of life is that occasionally something that you always saw as quaint suddenly becomes quite obviously not. One of those things is the extraordinary measures that people used to go to in order to prevent clothing moths from entering the house. All those little bowls of potpourri and sachets of sweet smelling herbs tucked away in drawers? Yeah, they were not because women had so much time on their hands that they had nothing better to do than sit around and sew dainty smelly things. Let me tell you. It was to avoid exactly what I am going through right now, which is engaging in furious and pitched battle with something about a million times smaller than I am. And yes, it is just about as ridiculous as it sounds.

You see, those various sweet smelling herbs, well, to a clothes moth, they smell like week old human waste, dipped in stink solution, which has then been vomited up and left in the sun for a while. In addition to that, depending on the herbs, they can actually kill the smaller caterpillars. This is not a quaint custom, it actually works. Potpourri was originally intended to protect the furniture in the room, which was often stuffed with horse hair or down and covered in wool. This same effect can be achieved by using sachets, and also by spritzing with essential oil blends. Some of the herbs and oils in question include: wormwood, lavender, cedar, rosemary, cloves, mint, camphor, orange or lemon peel (again, only if you don’t have cats or fish), lemongrass, eucalyptus, peppermint, thyme, and cinnamon.

For the larvae and eggs, the best prevention method is vacuuming. A lot. If they have nothing to eat, the moths will go elsewhere, and even small amounts of pet hair can keep a small infestation active. Vacuuming destroys eggs, as does taking your things out into the sunshine and brushing them. Light exposure will cause the larvae to drop off your garments, so this is best done outside. Remember, the adult moths don’t like light either, so exposing your stuff will keep them at bay as well. Doing this once a week often solves the infestation problem without need to resort to chemicals. But seriously, you might want to do everything listed here.

So, about those pheromones that attract the males? Well, some very clever folks applied them to some sticky traps. They attract only the males, which keeps the females and the eggs from setting up shop, as there is no one to fertilize them. This is an excellent extermination method, as well as prevention and monitoring. Simply set out the traps, and if you find any moths in it, you have yourself a problem. If you don’t find any, just leave the trap out for up to three months, and keep changing them out. These little cardboard tents also act as a kind of early warning system. If you do have an infestation, the number of males caught in the traps will tell you how fares the battle, and it will tell you (with reasonable certainty) when the battle is over. Keep putting out traps, however, for at least six more months. Better safe than sorry.