I agree with Diana and April. When we moved to our current old house, I didn't think to get the place treated for moths first. Well, there are moths. I've worked very hard to get rid of them, which probably isn't ever going to happen. I've settled on limiting their damage and have learned a lot about moths in the meantime.
Regular wear and cold temperatures mean moths aren't an issue, so winter in Canada is more or less a safe time. I don't take extra precautions in winter. It is storage where moths flourish.
I haven't had any wool losses in a couple of years, so I think my system is working really well. My system is basically two steps. Step one is to ensure there are no moths or eggs by proper cleaning. Step two is to make sure no moths can get in while also preventing cross contamination if step one fails.
So, step one, cleaning. Everything has to be cleaned. Regular hand washing and air drying won't kill eggs, so you either need to dry clean or, if you are handwashing, wash and then take the fully dry item and put it in the dryer on hot for half an hour. Wet wools can't stand the combination of wet, heat and friction--they will felt. But heat on dry wool isn't usually a problem.
After everything is cleaned, on to step two, storage. The science-based sources I've read (rather than word of mouth) say don't bother with lavender and cedar. They work very slightly, if at all. That's consistent with my experience. (Cedar closet. Moth munched clothes. Sadness for K. Period.) Moth balls work, but the smell is awful, so I don't use them. What I do is put all my freshly cleaned items in ziplock bags. For sweaters that I've hand washed, I use individual gallon size ziplocks because those are the items with the highest risk of eggs surviving. For things that I've dry cleaned, which I know the moths can't survive, I use big storage ziplocks (jumbo 20 gallon size) and throw a bunch of items in one bag.
I've been able to avoid any losses using my system. It's a pain, but much less painful that finding all my woolens have been munched on.
BTW, it isn't surprising to me at all that Mr. Suz's items got eaten and yours didn't if your things are store separately. Moths aren't good travelers. They flutter short distances and are really lousy fliers. They are wonderful hangers-on, hiders and crawlers, though. Mr. Suz probably bought an infested item (which could have been new from a store--there is no telling what might have eggs on it) and stored it without dry cleaning. Your sweaters were probably just too far away to get contaminated. For now. (Really. Seriously. Take precautions. Moths are like an infection. An infection that kills cashmere.)
