The beautiful demoiselle
By Charlotte Owen
Easily mistaken at first glance for a fluttering butterfly, the beautiful demoiselle is now on the wing. The word ‘beautiful’ is part of this exotic-looking damselfly’s official scientific name, rather than a mere description, and it’s very well deserved.You’ll know when you’ve seen one because it’s the only damselfly species with completely coloured wings - the closest contender being the banded demoiselle, which is also aptly named for the deep blue-banded wings of the males, as if they’ve been dabbed with a giant black marker pen. These two species both belong to the family Calopterygidae and are termed demoiselles (from the French for damsel) to distinguish them from the rest of the damselflies.
Male beautiful demoiselles are metallic blue-green with strikingly dark wings that appear almost black until the light catches them and reveals an iridescent blue sheen. Their flight is languid and twirling and their broad wings are easily buffeted by a breeze, so they prefer the shelter of well-vegetated riverbanks.Males tend to perch on a stem, wings held together along the body, lying in wait for a passing female.Her wings are a lustrous bronze and the metallic green of her body has a glimmering golden sheen.Females range up and down river in search of suitable egg-laying sites, so males establish themselves in prime locations and wait. As soon as a female enters a male’s territory he will court her with a fluttering dance and curl up his abdomen to display the bright underside of the last three segments, known as the ‘lantern’. Then he’ll take her for a tour of his chosen nursery site and if she’s suitably impressed the pair will mate, locked in a vaguely heart-shaped embrace for up to five minutes. Afterwards, they’ll flutter back to the water and he’ll fend off rival males while she deposits her eggs on aquatic plants, happily submerging herself in the process. The eggs take just two weeks to hatch but the stick-like larvae then spend two years underwater before emerging into the light and transforming into glorious adults.