You won't believe this one weird habit of bumblebees!

The bumblebees have this strange habit that I don't understand.Overnight, they latch onto the underside of the goldenrod flowers, and hang there overnight.  It gets cold enough for all of them to go catatonic, and they cling there overnight, curled hard and still as if they were dead, not reacting to being brushed or touched.This is not just  a few bees that get caught out too late.  There can be a dozen on one big goldenrod plume, and since we have a lot of goldenrod, in the evening and the morning, we can look across a swathe of it and see hundreds of bees, hanging still like odd fruit.  Then once the sun casts across them in the morning, they reanimate, and take up where they left off, buzzing, grazing, and bumbling.  Sometimes it goes badly- the weather will change, and I'll see them caught out in a cool or rainy morning.So weird!  Is this just a thing that they do?  Too busy to go home at night? They do it for many nights in the summer, during the goldenrod rush.