Of all the aquatic insects the dragonflies and damselflies are surely the best known. A few are instantly recognisable, but there are more than forty species in the British Isles and some of them are now very rare. Their irridescent bodies and aerobatic skills make for a fascinating spectacle on bright summer days.
Most damselflies have a one-year life cycle, while dragonflies are longer lived, some taking five years to reach maturity. The eggs, once hatched, become nymphs (also known as naiads), which live among submerged weeds.
In shallow lakes, the nymphs of damselflies are an important source of food for trout and other fish. Dragonfly nymphs, in contrast, are fierce predators and will attack and kill other aquatic creatures sometimes larger than themselves - we have seen them attack and kill a small newt.
When ready to emerge as adults, the nymphs crawl up weed stems and rest in the sunshine above water level until their outer shucks split to allow the winged adults to emerge. At this stage they are rather dull looking with pallid colouring.
The newly-emerged adults are vulnerable, because they cannot fly until their wings have dried and hardened. They remain very still - for an hour or more in very wet weather; then they take to the air, begin hunting for food (smaller insects) and become increasingly more colourful.
A recently-emerged Aeschnid dragonfly is shown here. The exuvia (the shuck or final nymphal skin from which it emerged) is also visible. Examining marginal plants and looking closely at any exuvia left clinging to stems is a good way of finding out which kinds of dragonflies live in a pond.
If you found this information helpful, you would probably find the new 2017 edition of our bestselling book Matching the Hatch by Pat O'Reilly very useful. Get an author-signed copy here...