I've put a few drops of lavender oil on cotton wool make-up pads, which I then put into small zip-lock plastic bags, leaving them unclosed. I put them at the back of shelves in closets, and haven't had trouble with moths since. The same trick seems to work with silverfish - I put some at the back of bookshelves. Eventually you need to renew the oil if you're still having problems, but it is worth trying, and it doesn't involve nasty chemicals!