On Moths

September 28, 2020

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47 Comments
  • Thank you, Kate, for such a terrific article. When my step-daughter went away to college, she came home with guests: moths. It was rugged to say the least. I “lost“ one of my favorite scarves which was knit for me by my friend Beth. Heartbreaking. I hope to never go through that again.

  • Moths! Several years ago when I got serious about knitting and my stash began to grow, I started storing my yarn in plastic bags. At the end of the spring, I wash all of my knits and store in bags. When I see a moth, I panic! But then I remember the measures I have taken. Recently purchased the pheromones traps and set them up before I unpacked the sweaters for fall.

  • Oh boy, you caught my attention with this article. I have had a moth issue that I think started with some rabbit fur pelts a fashionista friend wanted me to make a handbag out of (my gut said no and I should have trusted it). I tried everything – the freezer, the steamer, cedar, lavender, the sticky moth catchers. Everything is now in air tight plastic boxes. I read moths don’t like incense, so I burn that. I read they don’t like Irish Spring (the soap). So there is a bar in every container ( I really feel like it’s the 1970’s in my house). I also wiped every surface in vinegar.The icing on the cake was the parasitic microscopic wasps. Some blogger in the UK was talking about them so I bought them on Amazon (3 times). You can’t see them and they I think lay their eggs in the moth eggs. Anyway, the moth problem seems to be mainly gone, though they say if you have an old house you are always susceptible once you’ve had them . I will do one more time with my wasp friends and see how the winter goes. I don’t want to cry any more ( you notice I did not go into what got thrown away, but in the mix I did learn to needle felt cute polka dots that hide all the holes in my merino shawl).

    • This is a sincere question (not trying to be a jerk, honest) — if you can’t see the microscopic parasitic wasps, how do you know that you got them? I’ve just gotten very sensitive to being ripped off by third-party sellers on Amazon, so the question popped into my head.

      • A reasonable question! You can’t tell until it’s too late, which is why it’s so scary. You know when you either see the adult moths, or chewed-up knits. Prevention is crucial.

      • I know- I couldn’t tell, but the amount of moths in the sticky traps went from lots to almost none, so I am going to take it as a win!

      • Dawnmcd, I think your question is about the parasitic wasps, not the textile/wool moths? They are a type of Trichogramma parasitic wasps are used in the UK & Canada more commonly than The US. However, another type of Trichogramma wasp is very commonly used in the US in greenhouses to control certain plant pests. Biocontrol agents are well-researched before being released. If you do a little research I’m sure you can find the correct product from a reputable, non-Amazon seller.

  • Thank you, Kate. Moths are a nightmare! I had all my yarn in plastic bags and then I read somewhere that it wasn’t good for the yarn. Now back in the bags it goes. Not willing to take a risk with this lovely investment.

  • How timely. I have recently been plagued by an infestation of grain moths that led to a monster cleaning of the pantry. But, am now petrified about the wool!

  • Do you have a recommendation for pheromone traps? Just googled and there seem to be a variety.

    • Hello Cindy! There are lots of brands of pheromone traps, and they’re all good – just make sure you get ones that are specifically for clothing moths.

      • The “Mabel Grey” geranium is a moth deterrent and it smells lovely and lemony. Just started growing it so can’t personally attest yet to its efficacy

  • This is so timely. I’ve just worked through an infestation. Lots got thrown out and two favourite hand knits were ruined but I’m going to wash them and try to salvage whatever bits of wool that I can. I’d never heard of pheramone traps so am off to find some right now!

  • Don’t hate them, they are only living their mothy lives as best they can. That said, I have used the oven set to 200F for just a few skeins, but if you have more and your climate cooperates, a black plastic bag filled with wool and put into a sealed car in the sun will easily reach 130F or above. Leave in for a day, toss everything around, repeat a few times. They say just a few hours at that temp will kill both eggs and larvae, but I give things a good long bake.
    And for storage I highly recommend pennyroyal, a type of mint. I buy it by the pound (from Mountain Rose Herbs, but there are other places) and put in in little sacks made from pantyhose, each bin gets a few pennyroyal bags and I haven’t had a moth since. The odor is not toxic like cedar and mothballs, but it is not edible, so maybe don’t use it if you have toddlers around….

    • I’ve also successfully used the car oven method. Summer in the Central Valley of California is guaranteed to adequately heat a car sitting in the sun. My son brought home a “gift” of peruvian woven wall hangings that ultimately led to a massive summer-long clean and destroy project at our house. i cried a lot while I aggressively destashed and tossed lots of beloved FOs into the recycling bin.

      • I know professional conservators that have also used the car method in a pinch. Will work for almost all pests, be it moths, beetles, grain borers, etc. Be aware than dried plant material can have eggs of other pests that may cause problems. Perhaps you only get a the deterrent, but you could also get cigarette beetle eggs or carpet beetle eggs. Regular inspection is key!

  • My mother in law used to put conkers in with her wool. I think it started with a raw fleece but then when that worked she could be found every autumn under the horse chestnut trees collecting for her wool stash and jumpers!

  • One issue I have with items that need serious blocking is that I like to wash things. I know how that sounds, but I have never understood how you could wear (and maintain by washing) scarves and shawls with points on the edges that have to be pinned out to be seriously blocked. I’d spend my whole life blocking.

    And either I’m pickier than most, or clutzier than most, but I can’t imagine wearing a scarf a whole season without washing it.

    Another peeve – storing already-worn clothes with clean clothes. Not high on my list either.

    I will also add that moths may attack some things that they think is wool, but isn’t. When I was small (many moons ago) my mother made me a sweater from orlon – an old synthetic you don’t hear about any more. It was stored with some woolens that were attacked, and that sweater had holes as well.

    • That’s because the larvae are after various particles on the item, the fiber is ”collateral damage”! 😉

  • Thanks for being honest about killing them with cold. So many bloggers talk about the freezer as if it’s a magic bullet. I once left a moth infested plastic bin of wool outside for an entire New England winter, and the little buggers were still happily munching away in the spring. I think being surrounded by wool insulated them from the cold. Good ol’ wool doing it’s thing, I suppose. I have resorted to moth balls, but only in air tight vacuum bags. It was the only way I could think of to avoid throwing everything in the trash.

  • I don’t have moths, but I do have something just as bad: Pantry beetles. The larvae eat my yarn like nothing. Vacuuming and freezing does wonders, though.

  • This is especially true if you buy yarn at a stash sale or from a private party.

  • I own many Navajo textiles which I treasure -they are woven from the wool of churro sheep. Any suggestions how I should store/protect them? Currently they reside on a quilt storage rack covered with a sheet. I flip the ones I display on my walls and vacuum them all (no rotating brushes) once a year. I have read that another way to kill moth eggs in a Navajo rug is to put one into a giant bag with dry ice to remove oxygen, which is supposed to kill the eggs.

    • Sharon,

      My recommendations are the same no matter what the textile. Can you clean them? I would wash them properly, and store them in air-tight containers. As to the ones on your walls, make sure you shake them out fairly often. If they’re exposed to light and fresh/flowing air, those are less at risk.

      • You cannot wash wash Navajo textiles/rugs because the dyes are vegetable based. I would need to find a specialized cleaner – they exist in the Southwest not Kentucky. The rugs reside on walls or on the quilt rack, not on the floor. I guess my best avenue is to check them frequently. Thanks for your timely reply.

  • I picked up moths from a rug bought at a second-hand store. It has been a long fight! The Container Store sells both pheromone traps and a spray that I use to occasionally spray hanging clothes, rugs, under beds, yarn, and anything else I think might host the pests.

  • “For cold, you need industrial-freezer or winter-in-Minnesota temperatures—below minus 20°C/0°F.”

    Ha! This makes me feel good about the few days each year we are at that temperature or lower. A couple of years ago we had the infamous polar vortex and were at -20°F and colder for quite a spell. We Minnesotans are dreading the winter this year with the pandemic, so I’ll take any good news I can get.

    I have not encountered moths so far but if I do I guess I just set my woollies out in the yard in January and begone moths!

  • I’m curious about the oven method, and possibly making it a little less risky by putting the items in there wet instead of dry. My oven has a minimum of 170 degrees, and I’m wondering how long I would have to leave something in there to do the job. This is all hypothetical as I’ve never actually had any moth damage of my own (lucky so far, I guess). I will keep in mind pheromone traps (never heard of them before, thank you for the suggestion), and the “car oven” method suggested in comments (clever!).

    • Dawn, when I used the oven I set it to about 170F – warmer than the warm setting but below 200. I put a folded old bath towel on the rack and laid the dry skeins on that, being careful nothing touched the oven walls. It worked fine! I was mostly worried if it touched the metal it would char, that’s why I was careful about that. It has a sort of delicious smell as it heats. Just be sure no nylon or other synthetic, they will melt!

  • This was excellent and there is good information here. For people who do want to do a cold treatment, you need to be able to get the internal temperature down to -20C quickly and maintain it for 7 days. If you cannot you need to freeze for 2 weeks, thaw for 1-2 weeks, and repeat. That lets eggs hatch and then you kill new larvae. Eggs are hard to kill, larvae are not. For the heat treatment, 130F for 3 hours will do the trick and desiccate any eggs. As mentioned by others, the black trash bag in a hot sunny car can do the trick. An additional warning about lavender and other floral deterrents: adult carpet beetles eat pollen on anthers, so you can end up with eggs in the flowers and therefore introduce them to your stash where the larvae munch away on all your proteinaceous goods. (They can even live on the dust in your corners!) Keeping yarn and knits bagged can be helpful as pests won’t eat their way into bags generally, but will eat their way out. There is a lot of information on ID and these types of pests on https://museumpests.net/ and while as individuals we may not be a whole museum, the many of the practical applications apply. Sincerely, a knitter, museum professional and IPM person who threw away an entire giant bag of yarn when moving and has since been free of webbing clothes moths, black carpet beetles, and varied carpet beetles.

    • Excellent information and thank you for this link! I’ve used the freeze/thaw cycle and quarantine approach for some inherited yarn where I knew carpet beetles had been seen in the house; if there were any pests in the yarn, they did not survive. This would be a good approach for yarn from a resale shop or from an yarn swap too.

  • Carpet beetle larvae and silverfish can also be a big problem for yarn, even those with a synthetic content. Regular vacuuming of nooks and crannies keeps those pests out of natural fiber rugs and tapestries. On the Gulf Coast, where we fight insects all year, I put all of my yarn in the Container Store zippered sweater bags that are part canvas and part clear plastic…keeps pests out, lets natural fibers breathe, and you can see contents. Even with pest control, I check and vacuum the yarn stash bags regularly just to make sure no pests are attempting to get in.

  • Great discussion, especially about the “cold” treatment not being effective unless yiou can get the temperature below 0F. I’ve argued on-line with a lot of people about this, and I still see “experts” claiming that all you need to do is pop the yarn into your refrigerator’s freezer unit for a day or two.

    My biggest problem, though, has bee with carpet beetles. They will eat ANYTHING.

    Question: has anyone ever treated an infected item by zapping it in a microwave? How successful was this, and how long did the fiber/yarn have to be “nuked”?

  • My name is Carol. I am a knitter. I also live in a 220 year old house, which is worth mentioning because it’s craggy, uneven and full of nooks and funny places (especially the rock-walled basement that once served as the kitchen for this house in its colonial days). And … I have moths. I have been fighting them for years.

    I am not a fan of the pheromone traps because I think they can serve as a magnet for new moths. I do agree with all of the above recommendations about cleaning and storing hand knits. However, there is no amount of cleaning to fix a moth problem when it branches out across the whole house.

    The only pest control method that has helped me is not on your list: Trichogamma Wasps. Trichogamma Wasps are a parasitic bugs that lay their eggs in a moth’s egg, destroying the host. The wasps don’t kill adult moths or their larva, but goes at the source of new population – the egg. Many farmers uses Trichogammas for outdoor gardens to control destructive caterpillars. For use indoors they are the size of a pinhead, all but invisible, harmless to humans and pets, no sting. You won’t even know they are there.

    I order Trichogammas from an online organic gardening website and release hatching wasps every two weeks from March through the fall – every year. For me, the cost is a preventative measure, an insurance policy for my knitwear, woolens, wool rugs, linen drapes and that beautiful cashmere overcoat we bought for my husband at the Barney’s Outlet.

    In the world of pest control, I think any expert would say I am winning the fight given how few moths I now see annually, but it has been a multi-year battle. Every spring I see a moth or two but I haven’t lost any knitwear or home furnishings since I started releasing wasps 5ish years ago.

    Read up on these beneficial bugs – they are great for pantry moths, clothes moths and other garden pests. I have heard many people say they cleared up pantry moths with just one release. For clothes moths, I would recommend releasing every two weeks for several months, at a minimum, to make an honest attempt at disrupting the lifecycle.

  • Okay. Now I’m no longer thinking this could never happen to me. What got me is the part about tossing all the infected yarn! All that money I’ve invested! I just ordered moth traps for the moth listed in your article. Thank you

  • Moths!! I lived through a moth infestation (barely) 20 years ago in Brooklyn. It was winter when we noticed and I lost so many of my favorite sweaters. It was absolutely horrifying. Luckily this is before I started knitting. Since temperatures were below freezing at night we took anything and everything that could be affected (including my kids stuffed animals) and put it all in the master bedroom and flung the window open – turning the room into a giant refrigerator. After 48 hours, little by little I systematically took piles and ran them through the dryer to shock whatever larvae and eggs survived the cold with heat, before putting it away. It took about a week to get through it all – and have rugs cleaned etc. but we have not had a problem since. However, I live in fear now that I’m a knitter!! I recently stayed at an AirBnB with an infestation. We noticed then after unpacking our things and put everything right back in our luggage and zipped it up tight. When we got home we ran everything through the dryer. I put out pheromone traps. So far so good – but I can’t seem to uncross my fingers.

  • We had a horrendous problem a few years ago that we just could not conquer until we found the source. My partner’s parents’ antique Turkish rugs still in the overseas shipping containers in the basement, unopened for more than 5 years. When we got them outside and opened them there were so many moths that there was not any visible rug left. So gross!
    Just removing these boxes caused a miraculous disappearance from one day to the next. But I’m always on guard.
    Can anyone recommend actual “air tight” containers for our yarn, sweaters?

    • Wow! Also I’m sad for your loss of what were beautiful rugs!

      • I store wool in travel bags made by ziplock that you can use your vacuum hose to suck extra air out. If anyone knows why wool should breathe I’d like to hear it. I hope I’m not damaging anything.

        • Good idea and thanks!

        • Don’t vacuum until things are squished! I had some shetland wool that shed some fibers when I compacted the bags to fit the maximum amount of yarn in minimum space.

          Now I used those bags for superwash and other very smooth yarns (nothing rustic) and only suck out out enough air to get it roughly flat. Works a charm.

  • Getting rid of everything sounds foolproof, but extreme! After a couple problems I learned to keep my closets airy and light, no crowding clothes. Things I love are out in the open and examined regularly. Moths hate light and to be disturbed. They also prefer clothes with sweat or food stains. My yarn is in plastic along with clothes I’m not regularly wearing.

  • Hi, very interesting moth talk here!
    I do have moths in the house, and I know they like the underfloor isolation we’ve used, an ecological thick mat made from wood and cardboard. They seem to come from under the woodden floor anyway.
    I store all my yarn in linen/poly zipp cubes I’ve found at Muji. They are attractive and they seem to work well keeping the moths out. But over the years I’ve also discovered that moths really don’t like to be disturbed in their familylife! I find more moth presence in a pile of untouched laundry, unworn, too small clothes, needing to be sorted out, than there are moths in my knitted sweaters. I do check them twice a month and I do air them in the Summer, so I really keep a close I on them, and it seems to work. I did find one tiny hole in a lopi sweater. The more stuff you gather the more unlikely it will be handled/worn frequently. So let these little moths also be a lesson to hoard less, or take care of it lovingly (and FREQUENTLY ;-)… I actually doens’t take that much time, compared to knitting a sweater, does it?
    I do use sticky moth traps, scented soaps, (tea tree, lavender, cedar) and drops of cedar oil on wooden surfaces. Be sure no products touches your knitwear, as even lavender flowers pressed against the wool will be THE spot for a mothlarvea to munch a hole. Stains on clothes are a no go!
    And a little tip: overseen motheggs grow when they ripen, so just before they are ready, they are very visible, a golden/beige colour. Easy to take away with a brush or even your nails. Once you’ve disturbed them it’s unlikely they will come out. So keep bothering them, keep checking and handling your precious knits and the chance is they rather look for a better spot!
    A very old trick is a shoebox with a few small holes in it, put a few old wollen rags in it, and the moths will rather go there then in your other clothes if you keep them moving well. The box can then be burned with it’s content (or thrown away with the kitchenwaste). I’d love to try out the microscopic killer wasps too. But I’ve seen they are rather expensive…

  • Thanks for the excellent advice, and also the great comments. Especially regarding carpet beetles! I’ve had knitwear chewed, and occasionally yarn, but never seen a single moth. Ever!
    Which is when an experienced friend informed us about carpet beetles. Rarely seen, except when they climb the sheer drapes in spring, and when you see the new larvae during hatchouts. And renewed campaigns to get my husband to remove all carpeting. Constant vigilance!

    • We had a horrendous moth infestation after a dear friend brought a sweater over to mend at a mending party one afternoon.”I don’t know why,” she said, “this sweater keeps getting little holes in it no matter how much I mend it.”. Doom! She had had no idea. I had no idea. But two months later…. After a huge amount of research and talk with museum conservators this is what we did, WITH SUCCESS. We placed all woolen items, yarn, fibre etc. in giant clear plastic construction bags. To the bottom of each bag we added 3-5Lbs of dry ice. Then we tied the bags up tightly with 2 or 3 short lengths of the approximately 3/4 inch plastic tubing extending out of the bags. This detail is very important. As the dry ice melts (sublimates) it produces carbon monoxide and pushes the oxygen up to the top of the bag and out the tubes. This lack of oxygen from the carbon monoxide production kills moths, larva, and most importantly, eggs. The plastic tubing allows the oxygen to escape as the bag fills with carbon monoxide. Leave the bag(s) to rest for at least 24 hours.

      Best to open the bags OUTSIDE for safety reasons. Be very cautious not to breathe the carbon monoxide when opening the bags. But don’t be too paranoid- the CO dissipates very very fast and the yarn is perfectly safe to handle. And because some plastic bags are actually quite porous, I’d double or triple the bags for efficiency’s sake.

      Now all yarn is kept in clear plastic bags in clear plastic bins in the daylight. This treatment saved my huge yarn stash and while a bit tedious to perform, works perfectly. It saved shawls that had holes in them from having to be thrown out- with the eggs safely destroyed, the shawls were safe to mend and preserve.

      I hope this i formation is useful for someone. Please feel free to double check all this and correct me if you feel I’ve been in error.

      I still love my friend, btw!

  • I no longer knit or wear wool such was the drama and loss through the last moth ‘visitation’. I couldn’t seem to find the kindness to moths that I can extend to weeds in my garden ie a plant in the wrong place. So it seemed less stressful for all to sidestep. That’s required a compromise because no cotton or linen will look the same as a 2 ply wool fair isle. Not a solution for all, but it has brought me and the moths a truce.

  • Can you put infested wool in the microwave? Would kill the wee beasties I think but I’m not sure what it would do to the wool.