Red mason bees in close up

In previous years this little observation wing was attached to the side of my bee house but in the new position it doesn't fit so I have fixed it to the garage wall.

I was pleased when one bee started building in it and even more pleased when there were three, although it hasn't all gone according to plan.

The bees collect mud to fashion walls between the cells, making multiple trips back and forth.  The first bee was building one hole up from the bottom and made rapid progress, managing three cells on a warm sunny day.  She first measures out the cell and part-completes the wall.

Then she stocks the cell with a mixture of pollen and nectar.  The pollen is carried on a furry brush (scopa) under her abdomen and is delivered tail first by scraping the pollen off with her hind legs.  Once there is a bit of pollen she makes alternating layers of pollen and nectar, first regurgitating nectar from her crop and then turning round and delivering another load of pollen.  The bee can't quite turn in an 8mm round hole so has to return to the entrance but she can just manage in an 8mm square hole which saves a few moments.

Here is the bee bringing nectar and pollen on video.

Once the pollen and nectar is sufficient the bee lays an egg and seals the cell before starting the next one.  Here is a half completed wall.

And here she is finishing a cell wall.

A second bee started work one hole down from the top but was noticeably less agile and slower.  I think it had a problem with its right middle leg - possibly the leg was missing - and it made slower progress.  You can see the egg in the middle cell.  The darker goo is where the nectar has soaked into the pollen.

They were joined by a third bee which didn't seem to have much idea.  She kept checking all the holes, including the two in use which led to a few confrontations.  Eventually she started work in a middle hole but also started halfway along by building a complete wall first.  You can see there was even a false start in the hole above.

Then the weather turned very cold for a couple of days and top two bees disappeared.  The top one had completed three cells with one half finished and the middle bee hadn't even finished one.  The bottom bee also stopped work and sat around in one of the lower holes, not looking well.  When I checked a couple of days later she had disappeared as well but had sealed the hole before she left.  I suppose she realised she couldn't do more but wanted to protect the four and a half cells she had completed.  Looking at the photo I think there must be at least 15 mouthfuls of mud in the top layer so you can see what a lot of work is involved.