I placed an answer to a question and wish to retract what I said. I checked into the use of just plain grease patties all year long. After discussing this with a few old timers I found this is a very common practice, especially in this area. In this area it is the general consensus is that trachea mites have been the cause for winter kills more so than varroa destructor. What does everyone else think?
The use of unmedicated grease patties in hives throughout the summer is an acceptable practice. It seems the grease(vegetable shortening) confuses the adult mites and when they leave the host bee they cannot find another young bee to infest. Put your pattie in between your brood boxes and let the bees do the rest. Thanks for you previous post newbee.