I put the a swarm from Helen into Hive F on the evening of 2nd May. I had a look at the entrance and the removable hive floor this morning.
The colony appears to be settling in well, despite the colder May weather. There is shed wax on the removable hive floor; there are bees coming and going. It appears that they've been building comb and orienting themselves to their new area. I didn't look for pollen, but I wouldn't expect to see it this soon anyway.
I was very suprised to see a large number of Varroa on the hive floor. I counted 32, which is approximately 9 per day. A conventional bee keeper might urgently treat for Varroa in this situation. I'm inclined to wait and see what happens.
There may be exceptional reasons for the high level of mite drop in this new colony. They were contained for in the skep with a sheet under them before I collected so the varroa may have been shed over a longer time. I whacked the skep to dislodge them so that they fell in a heap on the hive floor. The fall of around 50cm may have dislodged more mites than would otherwise fall. Perhaps this colony is tolerating a higher number of mites. The parent colony seems to be thriving.
Introducing a new swarm to the apiary does raise concerns for me. This colony has not been feral for as long as the colonies from hives C, D and E. They may have genes which help tolerate Varroa and their attendant diseases but it is less likely. This colony may also introduce new strains of viruses which are present in the existing hives. There are known several strains of DWV. I consider this risk low because these strains tend to be geographically separate. It would be unlucky to introduce a new one. There is a risk of exposing the new colony to diseases already present in the apiary. I have seen evidence which suggests ABPV in Hive D.
I'll have to see what happens.