This is the damselfly that is seen most often on lakes and ponds in summer. The male, shown above, fully justifies the adjective 'blue'.
In contrast the female is a less conspicuous insects with green-and-black body colouring.
Mating damselflies form what is often referred to as a 'damsel wheel.
Paired damselflies can be seen flitting over the water surface and then settling on a floating plant leaf so that the female can dip her oviposotor into the water, attaching eggs to the edge of the leaf.