In central Mississippi, I have been told by an experience beek. If you have to treat for varroa, then do it late September and in February.
I believe my bees (Russian hybrids) have a low level of mites. However, I will have to do a sugar shake, as my sticky board tests have been compromise. I have been finding a few fire ants on the sticky boards. Funny everything else is stuck, except for those fire ants.