This will bee my first/second season with my 3 hives. So far, all are alive and well. They appear to have stores in the top box; all hives are 2 deeps and 1 medium. I checked the "panel" covering my 2 screened bottom boards and each had less than 25 mites. My other hive is a swarm I caught last July. They have consistently clustered under the inner cover and there are thousands of them. our temps have been 40's / 20's. What should I be watching for or doing for them? It is still a trudge in the snow and I cannot drive anywhere near them.