Hi: The discussion on border closing and the history has been interesting. In Montana, we first saw both mite species in colonies of migratory beekeepers. First a few, now virtually all (as far as I can tell) of these operators. In spite of regular treatment with strips, etc., we have no problem finding either mite. Until recently, most of our hobbiest and non-migratory commercial beekeepers have been free of Varroa, although Tracheal mites became more or less endemic. Packages or queens bought in the last 2-3 years are one potential source of introduction of T. mite to the colonies maintained by these beekeepers. This year, we have begun to find Varroa in hobbiest and non-migratory operations. Based on discussions with the beekeepers, I think hived swarms are a likely contributor to the problem. We suggest treating any swarms to suppress mites - the swarm may be a consequence of the natural division of a strong, healthy colony. However, the swarm may be from an infested colony that absconded from their hive. We have observed this response and have heard other reports of this happening. So -- a swarm may be a colony that left its hive. Why remains unknown. Perhaps it is a desperation move to purge the colony of mites. Possibly the mites influence bee behaviour, maybe as a means of enhancing dispersement. Whatever, swarms should be regarded as a likely source of mites. Jerry Bromenshenk The University of Montana [log in to unmask]