The horse chestnut (Aesculus hippocastanum) is in full flower so I have been looking out for bees carrying red pollen back to the hives. One hive was in full sun this afternoon so I watched with the camera.
This hive overwintered in a single brood box and had four frames of brood at first inspection 6 weeks ago. Since then it has expanded to double brood and a super, with 15 frames of brood yesterday. There were also several unsealed queen cells containing young larvae so I did a Pagden artificial swarm. This is the box on the original site with the queen and the flying bees and there were huge numbers of them. Not much pollen coming in, which is understandable as they don't have much brood to cater for, so I expect most were carrying nectar. I did manage to find a few with red pollen in the blur of activity.
Horse chestnut is the only local flower I know of with this colour pollen.
It was interesting to compare the activity at the entrances of the two halves of the split. This box was extremely busy whereas the other one, a metre away and rotated through 90°, was much quieter with a few bees doing orientation flights. I'll have to keep an eye on them both to make sure they don't misbehave.