The dragonfly and damselfly species found in the UK
Dragonflies and damselflies are both members of the order Odonata. Thre have been 57 species recorded in Britain, made up of 17 damselflies (suborder Zygoptera) and 25 dragonflies (suborder Anisoptera). Of these, 42 species (17 damselflies and 25 dragonflies) are resident breeders, and the remainder are either now extinct species, or vagrants. In addition two species, Southern Skimmer Orthetrum brunneum and Southern Darter Sympetrum meridionale have been recorded in the Channel Islands.
Dragon and damselflies live in a variety of wetland habitats, but always favouring those with good water quality, as most of their life is spent as underwater nymphs they require clear water in order to hunt. Various species favour different habitats, from fast flowing river specialists to those preferring still ponds and acidic bogs.
Fossils of very large dragonfly ancestors are found from 325 million years ago in Upper Carboniferous rocks; these had wingspans up to about 750 mm (30 in). In modern insects, the wing muscles move the sides of the thorax – and the wings move. But because dragonflies are ancient insects, the wing muscles are connected directly to the wings. This gives a much slower wing beat – 30-40 beats per second, which is why dragonflies make a noise like a little football rattle. However, this old flight system enables dragonflies to move each wing independently, making them more aerobatic. Not only can they fly backwards, they can also hover like a helicopter and perform hairpin turns at extreme speed.
They have two huge compound eyes – the largest eyes for their body size of all animals. The eyes are so large that they take up most of the head, and 80% of the brain deals with visual information.
Although damselflies and dragonflies are both members of the same family there are a few basic differences you can use to tell them apart, even if you aren’t sure which species you’ve seen.
Damselflies are smaller than a dragonfly, at rest they close their wings and their eyes do not touch at the top of head. Their flight is weak and fluttering, they don’t engage in aerial combat.
Dragonflies are larger than damselflies. At rest their wings remain open and their eyes touch at top of head. Their flight is strong and purposeful and are often seen as aggressive fighters in the sky.
Dragon and damselflies only leave the water to enable them to mate. They come together in a ‘wheel’ position in the air or on a plant. They then ‘oviposit’ fertilised eggs in submerged vegetation or directly into water in some species. The eggs hatch the following spring, and the nymph spends several years as fierce aquatic predators. When the nymph is fully grown, it climbs up a support, usually an emergent plant and the skin on the back splits, while the adult dragonfly slowly emerges. It has been estimated that 50% of those that emerge are unsuccessful due to predation in this vulnerable time. Newly emerged dragonflies are immature or ‘teneral’. They are thinner and paler and it takes a few weeks of feeding and sunny weather before they are fully mature.