First, on flowers: Bees love general ’ meadow flowers’ -yes, they are simple creatures 
, and they go bananas with lavender, rosemary… and garlic! (they get something from lavender, and the aline from garlic, that makes them high 
They love also apple, almond, cherry and chesnut tree flowers. Bees are picky also; at the beginning of the season, they prefer pollen-rich flowers, whereas later in the season, they prefer to collect more nectar.
And then, on swarming… Imagine that you say one day to your kids ‘Children, we are too many in this house, we are moving out’, and 2 days later, you have organized 30,000 people to follow you to your new dwelling, who, by the way, have eaten all of of your fridge and pantry reserves. Well, it does not translate so well to humans… but this is what happens:
Prior to anything, bees, like humans, go house-hunting. When the Queenbee gives the notice ‘hey girls, we are swarming’, there is a task that is given to about 2 to 3 dozen bees – they will not collect nectar, they scout the surrounding areas for suitable locations to build a new hive. And it may take a couple of weeks. They look for holes in trees, or in urban structures, with roughly a volume of 30 -50 liters. How do they measure the volume? They walk and fly inside the hole, calculating the volume based on the time they take. Smart girls! And, like humans, they are picky! they prefer those with East sun-exposure, landing ground and easy access (2 -3 meters cleared entrance), clean of other ‘tenants’, at least 2 m away from the floor, and at least 200m away from their current hive. Yep, they also want the relatives close, but not too close! When a bee-scout finds a suitable location, she calls the other scouts for a second visit, and they decide together if that is going to be their new home. If yes, they come back, announce it to the Queen, and then the date of the moving is decided.
The Queen gives the last notice of swarming, by piping, everybody gets ready. The first notice is usually known by everybody much much earlier (one or two weeks in advance), but there is a count-down of 72 h within the beehive prior to the actual swarm. During these 72 h, all of the bees who are ‘called’ to swarm with the old queen, gorge in honey. They pig out and eat as much as possible, because they will spend now up to a week flying away, feeding the queen, posing themselves in strange locations, and focusing on keeping her warm and settling on a new nest, so they need reserves. Prior to a swarm, the colony eats (on average) 6 to 7 kilos of honey…in 72h!!!
When a colony swarms, about half of the worker bees leave with the Queen. Out of the 60,000 bees, which ones leave, and which ones stay? How is it decided? How does each bee knows it? The entomologists do not know it for sure. They believe that the bees who leave with the queen are the foraging bees (>25 days old), and the ones staying in the hive to attend the new princess (to be born) are the younger bees. But nobody knows for sure. We don’t know for sure, but each of the bees know in which team they are -stay or go- because they pig-out or not, and leave -or not!. What we know for sure is that, during the 72h count-down time, the bees also stop feeding the Queen, and start chasing her around, so she exercises and does not lay more eggs. Why? because the Queen, otherwise, is too fat and heavy to fly! She needs to leave the colony and fly away together with her chosen ones, so the working bees keep her on a strict diet. This is the reason why also the swarms ‘rest’ in strange locations before reaching their already chosen new home - the queen bee is still ‘chubby’, and cannot fly for long periods, so the whole swarm accommodates to what the Queen can fly! Isn’t it incredible?
On the next chapter…what happens with the kids when they are ‘home alone’? (because the Queen mother, before flying away, leaves viable pupi of future Queens (usually between 3 - 7). But there can be only one Queen… how is it decided? What happens with the other sisters?..How do the virgin Queen choses its future partner?.. all this and more, on the next installment!
Meanwhile, you see here how I lure my swarms. Who wouldn’t be attracted to stay in my home-made swarm trap! 
yep, every yellow box is a beekeepers’ registered location, with at least one hive. But usually more, with an average of 4 hives per yellow box.