I have seen fluvalinate fail us in the 90's and after a hiatus of some years, become once again effective in economically reducing the mite population. I would think that the non-resistant mites breed back into our gene pool and the general mite population at a future date succumbs to the miticide. So one could surmise that a miticide's effectiveness for varroa control isn't chiseled in stone. k Kirk Jones Sleeping Bear Farms beekeepers making honey... Benzie Playboys cajun and zydeco band........ Beekeeping Journal Blog thoughts on beekeeping Facebook *********************************************** The BEE-L mailing list is powered by L-Soft's renowned LISTSERV(R) list management software. For more information, go to: http://www.lsoft.com/LISTSERV-powered.html Access BEE-L directly at: http://community.lsoft.com/scripts/wa-LSOFTDONATIONS.exe?A0=BEE-L