A warm day on the flowers there are insects, a bit like a wasp or a bee, but with only two, and not four wings. When they are frightened off, they do not immediately fly away, but hang in the air above the flower and only then rapidly move to neighboring flowers.
These are flies from the family Syrphidae. They are unusual because they masquerade as dangerous insects that can stand up for themselves - wasps and bees and have a yellow striped abdomen.
