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Hyer Wools Blog

Protecting Wool from Moths

We fiber addicts are very concerned about how to prevent moth damage to wool. Most of us have lovingly prepared fiber waiting to spin and irresistible yarn collected in a stash for an upcoming project. We keenly feel anxiety that this valuable wool yarn and fiber is vulnerable to those treacherous clothes moths. But our options for truly protecting our wool have shrunk because of the poisonous nature of the time-honored moth ball.

Moth balls are very effective at repelling moths in clothing. Our grandmothers used them freely and sometimes that unique fragrance triggers loving memories, but we know now that even the odor is toxic! Naphthalene, the chemical historically used in moth balls, is a solid white substance with a strong smell. The solid gradually breaks down into a gas. How naphthalene actually kills insects is not completely understood, but scientists do know that when the gas is inhaled, the chemicals react with our red blood cells, changing them so that they can no longer carry oxygen. Severe exposure to the poison will simply kill the red blood cells. Cancer studies with animals have also suggested that naphthalene can cause cancer and the EPA has classified the substance as a possible human carcinogenic. Naphthalene was initially registered for use as a pesticide in 1948 but, while still available and quite effective, very few people are willing to use mothballs these days.

Paradichlorobenzene is a second strong smelling chemical often found in moth repellents. Like naphthalene, it is a solid white substance that breaks down into other compounds in the human body. It is dispersed in the blood and fat cells, found in breast milk and excreted in urine. Also like naphthalene, it is harmful to cells and organs, particularly the liver.

Thankfully there are alternative methods to protect our precious fiber. But the regrettable truth is that these are simply not as effective as the poison. I guess that makes sense, but our health is the trade-off. Here are our alternative choices for controlling moths and these are largely based on an understanding of moth behavior.

#1 - Plastic bags or boxes that are tightly sealed. Begin with a clean container and then seal out the insects. This is actually the most reliable method of preventing an infestation. Woolen yarn and prepared fiber, such as batts and roving, can easily be stored in tight-fitting plastic storage tubs. Plastic bags tied at the neck and then sealed with tape is another choice. Hand-knit woolen garments and accessories can also be stored in these boxes or sealed in plastic garment bags.

#2 - Herbal Sachets. Various herbs have historically been used to help repel moths in wool. The effect is unfortunately much less than using the poison. There is not enough scientific evidence to prove these herbal potions are effective, but the historical precedent urges us to use them anyway. Apparently, the female moth uses an olfactory sense to find an appropriate spot to lay her eggs. Strong scents can disturb this process. Many of the traditional moth herbs are in the artemisia family; southernwood, sweet annie, wormwood and tarragon. Cedar and lavender are also effective and smell lovely. Other herbs such as lemon verbena, french marigold, coriander, pyrethrum, and pennyroyal are also useful in a moth sachet. Just combine any of these herbs in a loosely woven bag and place with your stash of wool and yarn. I've used herbal sachets with my woolens for many years and have successfully kept the moths at bay. I'm happy to share directions and some of my recipes for creating an herbal moth sachet in an upcoming article. Watch for it.

#3 - Another alternative to moth balls is to practice good housekeeping. I know it is a pain in the neck, but preventing the clothes moth from getting to your fiber is much easier than dealing with an infestation later on. Adult moths are not strong flyers and they hate bright light, so don't create prime habitat by keeping piles of wool and yarn in a dark corner or on a high shelf in a seldom-used closet. Stir around in your stash regularly and admire all your pretty yarns. Reorganize and fluff the piles, move things around. This will disturb any moths and hopefully you'll get a heads-up before the situation gets out of hand. Woolen clothing (and by extension our woolen stash) that is in constant use is far less likely to be damaged since any infestation can be detected and dealt with.

If you discover moths in your stash, brush the insects off the fabric or yarn and then freeze the article by placing it in a plastic bag in the freezer. Hold it at 18 degrees or colder for several days, bring it back into warmth and then freeze it again. The shock of the two extremes will help kill any eggs that may be left on the article. Infested drawers and closets should be completely emptied then cleaned thoroughly with regular household cleaner.

While the moths certainly eat clean woolen fiber, they are even more attracted to the other organics associated with the fiber such as lanolin, oils, dirt and sweat. Don't store prepared fiber and yarn in the same area as raw wool fleece and always wash or otherwise clean woolen garments and blankets before storing.

#4 - Finally, use your stash. I know it is hard to resist buying more wool, but a very large stash is simply a potential source of infestation. If your stash is so large that you find it hard to inspect everything you simply need to quit accumulating and start crafting!

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