Once you have moths in your yarn stash, there are several steps you can take to eradicate the little monsters and keep them from getting to the rest of your precious wool.
- Assess the situation. Determine how much yarn is affected and the extent of the damage. If balls have been eaten to pieces, the best course is to throw them out. If some yarns that were in the same storage container don't appear to be damaged, put them through decontamination anyway. If yarn in other storage containers appears untouched, its up to you if you want to "clean" it all. Certainly keep an eye on any yarn that seemed unaffected to make sure the pests didn't spread.
- Freeze or heat your yarn. According to the pest management guidelines provided by the University of California, infested yarns (or completed garments, for that matter) can be heated to a temperature above 120 degrees Fahrenheit for at least 30 minutes or can be frozen at temperatures under 18 degrees Fahrenheit for several days to kill the pests. I have heard that some people keep all their wool in the freezer, but that seems a little excessive unless you have a very valuable collection of yarn.
- Spray if needed. If for some reason you don't want to or can't heat or cool your yarn, you can use an insecticidal spray to get rid of the moths. Pyrethrin is a good choice because it is organic, fast acting and quickly degrades. It is made from chrysanthemums and is a good choice for hard-to-kill pests. Check that the product you are considering says it kills clothes moths, and follow the instructions on the package to use it.
- Prevent future problems. Losing some of your stash to moths is a frustrating and heartbreaking experience, but it's one that doesn't have to be repeated. Take care to properly store wool in the future by using air-tight containers and keeping the room your wool is stored in clean.
- Check up on your stash. Having a moth problem is a sign that you need to pay more attention to your stash. Especially if you have containers of yarn you didn't treat after the infestation, check in on those yarns regularly to make sure the damage hasn't spread. And at least once a year take all your yarn out of storage and make sure there's no damage. If nothing else, it's a good excuse to revisit your stash and maybe become inspired to use some of it!