Reminder on hygiene...Quite a few people seem to have just left dead-outs uncleaned and open after last winter. If Nosema was the issue that will spread it. Likewise, but less likely, one of the (notifiable) foulbroods.
Setting up bait hives should involve a scorched brood box or equivalent and an old broodcomb with no residual honey/sugar "honey" from a hive of known health....and not a hive whose residents have died. It is a bad idea to leave combs in hives for robbing out. Disease spores are easily spread that way.
I visited a house last week where bees had moved into both the eaves above a toddler's play area and the chimney. The previous "beekeeper" had just moved away leaving her residual hives behind in the wood. There was even a pile of old frames and combs slung in a heap. The new householders knew nothing of bees - and really didn't want to.
We have a duty as beekeepers to look after the health of our charges, not to spread diseases and to keep up to date with how to keep things so. Lots of info on Beebase including downloadable free booklets on the Foulbroods and Varroa - essential reading.