I have spent many hour's sat on the banks of my favourite New Forest stream watching these lovely insects flying in the sunshine, they catch small insects on the wing, then pitch to eat there prey. Males have a metallic blue-green body with purple-brownish wings, females have a metallic green body, and the brownish wings have a white spot just above the end of each wing.
The aquatic larvae take 2 years to mature. Demoiselles can be seen from May to September along fast flowing rivers and streams during the summer months.