Adding Winter Patties To A Hive

I put winter patties on some colonies today. The weather was perfect to open a hive. Nice and sunny and no wind. A couple colonies were short of food. I could tell these hives were light on stores by all of the bees in the top box.
 Right now the bees should still be in the bottom box. In some colonies I could see the bees down deep between the frames, this is fine. That is a sign of ample food stores.
But, when the bees are covering the frames in the top box, they need food.