Yeah it seems these mites spead south to north and now since they basicily all come from the same seed,you mite say,there resistance to the aspeian strips is spreading the same way,I live in a spot which doesn't have any commerical bee hives and very little of any hives,but it caught up with me and it will be up there to,your cold winters help slow them,no doubt.Hell the medicine to treat these mites may do more harm than good in the long run,who knows? RICHARD GAUTHIER