Hello

I am in the process of regressing my colonies for foundation-less bee keeping.. All my bees seem very hardy and were splits from what appears to bee a strong locally adapted hive I have had for about 3 years. These original bees seem to be resistant, so I began to make splits in the spring. All split seem very strong and I am regressing them to pull foundation-less comb and YAY they are doing this well. The original hive is not regressed on any frames. Should I treat this fall? If so what "soft" chemicals would you recommend.

Secondarily I have a screened bottom board on only one colony. Can you leave the screen exposed all winter? and can we generally use SBB in Maine as it is such a cold winter climate.. All advice appreciated as usual!!