Gloucestershire,
United Kingdom 
UNUSUAL BEHAVIOUR OF WASP-LIKE INSECTS
The insect appears to be a small variety of wasp with their typical shaped and yellow ringed abdomen approximately 14 mm head to tail plus antennae.
One normally sees the common wasp being active round the entrance to their nest leaving and returning and potentially dangerous if disturbed.
I first noted these insects about a week ago on the lawn of our cottage in Hopton Rd. Cam. The swarm were mainly concentrated in an area about 10 feet in diameter hovering around about six inches above ground level and did not appear to be worried when one walked about them. Any idea as to type? Has anyone seen similar
7 Sep, 2017
Answers
Appears to be a ground bee. No bee hives here since it is a solitary nester but you will see these solitary nests (multiple holes in the ground) close to each other. They are a peaceful sort.
8 Sep, 2017
is this not a hover fly it disguises its self to look like a wasp but has no sting ?
8 Sep, 2017
You mention 'swarm' which is confusing. I'd say ground bee, because they do hover above the ground, especially if there's been some heavy rain, but not in a swarm, so maybe you were seeing a few doing it at the same time, which is not unusual, but its not a swarm - that's a massive number of bees, usually honey bees, with a queen, who've left the previous hive or nest to start another one, and they don't hover above the ground. They fly together en masse and if they land, its usually on a vertical surface, not a horizontal one.
8 Sep, 2017
I also think it is a species of ground bee and nothing to worry about really.
8 Sep, 2017
I'm in the US but this looks like a honey bee. Several factors affect their behavior such as temperature and maturity level.
8 Sep, 2017