Swarm/robbing

[Terry N]

On this afternoon, Sunday, at one point, seemed like low activity, about 1 hour later, many bees as though many was born....anybody guess why so many bees? Then after a short while back to low activity.

[kathyp]

probably orientation flights.  they tend to take place in the PM and can involve a lot of bees.  you will see them crawl up the front of the hive and fly facing the hive, up and down.  over a period of time they will increase the distance of their flights.

[BlueBee]

I agree with Kathyp.  If you see a bunch of bees flying around in front or your hive, it’s an orientation flight.  If you see a big cloud of bees ABOVE your hive, then you’ve probably had a swarm.  That cloud will fairly quickly go to rest in a nearby tree if it is a swarm.   Look in the trees if you've just had a big cloud above your hive/s.

[L Daxon]

Kathy is right. Usually orientation flights. 
If it is a swarm, the number of bees will grow in an ever larger whirlwind and eventually take off.
If it were robbing, you would see bees fighting and rolling around on the ground outside the hive.

[Terry N]

Well thanks....you just taught me something new!