Vandieman, My guess would also be mites. If you go to your state beekeeping forum, located at http://wabeekeepersforum.proboards.com/ , you will see a question regarding losses for this winter. There are some very experienced beekeepers there and so far, almost everyone has lost 25% of their hives. Like it or not, most of the losses of beehives in this country are caused by mites. The summer of 2015, due to the very early spring, the drought and all the other factors, appears to have caused the mite to multiply very early and by the time folks treated in August, the usual time to treat here, it was too late. As stated before, we all want to be treatment free but if the hives are dying from mites, treating is the only option.