Just this morning, I strolled into my craft room, a place I treasure and try to take great care of, to find yarn supplies for an exciting new project. Little did I know, that my fond thoughts were not enough to protect my collection of yarns from around the world.
A bit of research landed me on the university of Kentucky's Dept. of Agriculture "Clothes Moths" page. They describe the moths like this: "The larval stage (pictured right) of clothes moths are creamy-white caterpillars up to 1/2-inch long. Webbing clothes moth larvae spin silken feeding tunnels or patches of webbing as they move about on the surface of fabrics. The casemaking clothes moth encloses itself in a portable case that it drags about wherever it goes. Damage to articles may consist of irregular surface feeding or holes eaten completely through the fabric. Oftentimes, the larvae leave the material they developed on and can be seen crawling slowly over walls or ceilings."
Inspect and isolate. The best thing you can do for yourself is inspect new yarn coming into your house and isolate it right away. Store in thick plastic bags or airtight container away from your existing stash. This will prevent spreading should there be eggs. Be sure to remove all air from bags. The scary thing is, these moths don't stop at balls of wool, they will find your unprotected knitted blankets and sweaters. Be sure to look through your finished garments as well.
There are discussions of methods to kill the bugs such as freezing and drying, chemical use and moth balls. My research leads my to believe that these are if not tales, dangerous for the recipient of the knitted item. Mothballs tend to discolour natural fibres and chemicals can be harmful to skin, especially newborn babies, whom we love to knit for.
If you are faced with this yarn stash dilemma and are contemplating on keeping some stuff that might not be infected, let me help you. Throw it out. Right now. I will wait here and console you when you return. Heck, I'll even drive you to the yarn shop to replace the colourful balls of wool that were going to be something amazing.