The season is ending for the beautiful demoiselles (Calopteryx virgo) and it is time to prepare next ones.
To do so, they form a nice heart where the male, entirely metallic blue, holds the female “neck”, while the female, with dark brown iridescent wings and a metallic green body, curbs its abdomen to receive the semen.
Mating takes place in a way that for the genus Calopteryx and is typical of an eye-catching advertising behavior. The females fly over the water, always in search of suitable nesting places and fly it through the territories of males. The males who recognize the females to the reflections of the moving wings fly towards it, once they have crossed the border area. It shows the last three segments of its abdomen which are much brighter and are referred to as a "lantern" that will be presented. The male leads in this way, the female to the nesting sites ("Show flight") and circled it on the water once it has settled out.
Females lay up to 300 eggs at a time on emergent or floating plants. The eggs hatch after around 14 days. The larva, called nymph, is stick-like with long legs and develops over a period of two years in submerged vegetation, plant debris or roots. They usually overwinter in mud or slime.