The varroa mites can really build up in our hives this time of year and if we’re not careful hives will be lost. I have started weekly dustings of the hives with powdered sugar. This loosens the mites that are attached to the adult bees and they fall through the hives’ screened bottom boards and onto the ground, where, hopefully, the fire ants will eat them. I’ve tried different chemicals and medications to kill the mites, but as you might guess, that which kills the mites also kills the bees. Not good. Powdered sugar dusting isn’t the most efficient way to kill mites, but it’s the only way I’ve found so far that doesn’t kill my bees.
It’s easy to spot the white powdered bees, especially when they fly into the wrong hive. When you have some bees covered with powdered sugar it makes them easy to track, and it’s interesting to see just how frequently bees will fly in and out of hives that are not their own. “Robber” bees will usually be attacked and driven out when they enter their neighbor’s hive, but bees covered with powdered sugar seem welcome wherever they go.
Gretchen Bee Ranch 
Have you tried Apiguard? It’s a thymol based slow-release gel that won’t kill your bees. It works well in hot temperatures and above 25C (77F) you only need a half dose. Only use it once your supers are off, otherwise you get thyme flavoured honey!
Mark’s going to try that this fall, Emily. Thanks.