Here is a good write up about bee biology with winter bees over summer bees. https://drive.google.com/file/d/0B19LtAPiDZi5OTlNcFVQYWFGMGs/view?fbclid=IwAR0IOFMi3EyGaP5S-mqTYF_XQAZECrYPYmv87ZMntnaPGeJXKFletPIyf-g