Dragonflies can begin to emerge as early as April. In the UK, we have 36 Species of Dragonfly and 21 species of Damselflies, both from the insect order Odonata.
Male Broad-bodied Chaser Dragonfly: Ernie Janes (rspb-images.com)
Two ways to tell the difference are with regard to wings and eyes: at rest, Damselflies have their wings upright, as butterflies do when they rest on a flower but dragonfly wings are left open, horizontal, down and flat.
Damselflies have two distinct eyes with a little space between them but a Dragonfly’s eyes join up enabling them to have almost 360˚ vision. The dragonfly’s eyes are the largest in proportion to the head of any creature in the animal kingdom taking up approximately 80% of the entire head
Dragonflies have a slower wing beat of approximately 30-40 wing betas per second. This is slow compared to other insects for example ladybird’s wings beat approximately 90 times per second, a blue-bottle fly approximately 150 times, a bumble bee around 200 beats per second. Dragonfly wings also each beat independently rather than in pairs like other insects so the slow wing beats and independent fluttering is why we often hear a dragonfly before we see it.
Eggs are laid in or around water from which the tiny nymphs hatch. They will live in the water anything from 2 months to 5 years depending on the species and then crawl out onto vegetation for their final skin moult into the adult Dragonfly with wings. Some fascinating footage of a dragonfly emerging filmed by Andy Hoult for BBC Wildlife Magazine, can be viewed online here: https://www.youtube.com/watch?v=hzS5MHx_PoQ
There is a helpful guide to Dragonfly and Damselfly identification and lots more information about their life cycle on the British Dragonfly Society website here: Damselfly /Dragonfly Identification …and for us gardeners, you can find tips on how to make a pond area particularly attractive to dragonflies here: Ponds & Dragonflies: Tips.