reminder that if you ever buy wool yarn secondhand you should put it in a plastic bag in the freezer for a week, let it thaw 24 hours, then refreeze another week. this makes sure that if there are any moths or pests they are killed by the first freeze, and the remaining eggs are lured to hatch by the thawing and then killed with the second freeze. until this process is complete you must keep the yarn isolated from your existing stash or you risk any infestation spreading. i buy a lot of wool yarn from thrift and antique shops and always do this and have never had a problem with moths or other bugs. if you buy wool sweaters or other wool things secondhand you should also do this just to be safe
I do this with all my secondhand wool fabrics, though with a week of thawing because that's how long my mother said to do it.
It also applies to feathers and especially fur! In the hierarchy of moth tastiness vintage furs are very high on the list. They like fluffy things better than smooth tightly spun things, and they like dirty things better than material that's clean and full of sizing, so old furs are extremely edible as well as full of hiding places. And they will eat feathers, I've seen it :(
I'm told that they will also eat silk but only if it's sufficiently dirty.
When you do this, remember to tell your housemates, otherwise you will get woken up by a very concerned and confused shout.
