I simply stack up the supers outside with frames and combs, and unimpeded air flow prevents the problem. Wax moths hate air flow, and sun. It's worked for me. I just used two 1x2's inbetween each box (sometimes bed slats ... hey, it's what I had on hand at the time), but it was during winter. Rain was not a problem. Just put a top on the top box and the air flow will dry out any combs on the edges that get a little rain.