Demoiselles (Calopteryx virgo) are in large number those weeks on the creek side. Like flying sapphire the blue males are chasing themselves and stop from time to time on the plants of the bank or on my hand.
Not so easy to shoot them when being on my right hand.
Demoiselles and dragonflies ancestors appeared on Earth more than 300 million years ago. Thanks to the higher oxygen concentration at that time, they managed to be giant insects, more than 70 cm wide.