I don't usually feed my colonies. I'm especially cautious about feeding swarms because they arrive with honey which can contain spores from a variety of diseases including the devastating American Foulbrood. The usual advice is to leave the bees alone for a week. They will build comb and use up the honey which they arrive with.
When I put Colony 17 into their Commercial hive body I had too few full-sized frames. I increased the number by putting in shallow frames from a super. Yesterday I quickly opened the hive to replace the shallow frames with full-sized deep frames.
It was quite cold yesterday, with the temperature only briefly climbing above 13C. The colony was clustered in one corner; there were very few flying bees; there was no sign of comb building. Had they run out of stores? There is still forage around -- the wild roses are in bloom and the Elder -- but we are approaching the 'June Gap'.
I decided to feed them with sugar. They discovered it very quickly. I hope that it will replenish their energy so that they can forage when conditions improve. I don't like feeding because it may disrupt the normal behaviour of the bees. On this occasion I've relented.