> For many years I went by the old adage that bees fly when the temperature is above 50 degrees and don’t fly when the temperature is below 50

I've seen foragers out at temps below 50F as well. That's the beauty of complexity within the hive. Multiple patrilines ensure you have a wide variety of response to stimuli. Some foragers will fly down into the 40s, some not until it's warmer. 50F is more like a guideline; it's a good estimate/generalization.

I have a photocopy of a schematic of bee activity by temperature from Sammartaro & Avitabile tacked on my board. At 50F, it notes "brood rearing stops, workers cannot fly." Works for me as a general gauge. Of course, brood rearing continues within the warmth of the cluster (noted to form at 57F) when outside temperatures are below freezing. At 42F it reads "Bees cannot move; muscles are not hot enough" and at 40F it reads "Bees die if alone." 

S

Skillman, NJ

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