Having lain my flybox of caddis flies on a log on top of my vest one hot day, on the Snake in the Tetons, only to find it missing the next day with all my caddis dries missing, I've changed my mind on storing flies. I, also, found that the hooks on my Elk Hair Caddis stored for several years had rusted at the contact point with the foam in my fly box. (They had apparently gotten moisture and rusted over several years). Currently working as a USFS campground host outside of Yellowstone, I find most of my tying needs to take place at home with my lighted bench in the winter. I store my newly tied flies in those plastic compartmented boxes in the craft store. I label them by fly types. Then select smaller numbers of flies for fishing trips as needed. I restock out the "bins". I trade early mayflies for later ones as the summer and as conditions progress. A zillion nicely tied Royal Wulffs might look nice in a magazine, but are not necessary when 4 or 5 max would work for an afternoon of fishing. If lost-your out of luck or if they get wet, they might ALL rust over time. I use the smaller pocket size fly boxes with a variety of a few in each type. If dunked, I'll usually remember to dry, if lost, I've got replacements and restock that evening back at camp. I purchase the large "bead-jewelry making" container at a craft store- usually $1.50-2.00 each with plentiful coupons. I store these in a large storage container at my camper. When I tie at home, all I need to do is look at my container labeled (for example) Stoneflies & Large Attractor Nymphs to see how many of each pattern and size I'll need to tie that winter. As the summer progresses, the Stonefly nymph container goes to the bottom of the bin and the "Hoppers" container moves to the top.