Sub Zero Next Week

Next week according to WCCO weather, we may be having subzero weather for two to three nights. Nights like this are colony killers during the month of February. With the warm weather a week ago, brood may now be present in bee hives. The queen usually starts laying eggs in early to mid February. If the queen started laying over a week ago, a little earlier than normal. There may be a decent size patch of brood in the colony right now.
  When it is warm the bees may be able to move easily in the top box.
Sub-zero temperatures, can pull bees off of an adjacent frame of honey to keep the brood warm. The cold forces the bees into a tight cluster.  If the extreme cold lasts for two to three days, starvation can occur.
Winter patties can help prevent starvation from happening. The cluster can get on the patty and consume the sugar to feed the brood if they pull off a frame of honey.

The bees do eat winter patties. I put the patties where the bee are. In this case the bees were still in their lower box, so I put the patties there.

This colony was light on honey and I put a shim on the hive and loaded up the winter patties.