We've had a couple of days which have been warm enough for drones to fly freely, so hopefully the new queen should be well mated by now. They mate with a dozen or so drones, and need to get the number reasonably high or they fizzle out over the winter. I've lost a lot of colonies that way in the past, but waiting till late summer or early autumn seems to be giving better results so far. Hopefully I've now got the four hives headed by well-mated queens, but since three of them were raised this year, it's impossible to be completely certain.
I've dosed them all with sugar syrup containing fumidil-B, an antibiotic derived from a fungus called Aspergillus fumigatus. It treats Nosema, a bacterial disease of the bee's gut, which shortens its life and leads to the collapse of colonies over the winter. I've no proof that my bees have it, but I'm suspicious, and I don't currently have access to a microscope. It'll do no harm to be certain.