By Henry Cook – Assistant Warden – RSPB Fen Drayton Lakes

With the rising mercury, long summer days encourage an ancient group of insects, as old as the dinosaurs, to take to the air. Dragonflies and damselflies, collectively known as odonata, emerge out of the water following several years as a nymph, climb up stems and emerge as an adult. At this time, smaller insects better watch out as odonata are experts at hunting, partly due to the 30,000 facets that make up their eyes so they can see in incredible detail. They also power each wing individually (unlike most insects) which gives them great dexterity in flight, being able to hover and even to fly backwards. Thankfully, they pose absolutely no risk to us, and indeed they appear wonderfully colourful, patterned and even graceful.

There is an easy way to tell if the individual you are looking at a dragonfly or a damselfly. If it holds its wings open, away from the body, it is a dragonfly. If they are held closed, in line with the body, then it is a damselfly. This sounds like a pleasingly simple rule; however, nature loves exceptions and there are a few, but they are thankfully uncommon. The other general rule is that dragonflies are bigger, being quite chunky, whereas damselflies are much smaller and slender.

Hawkers, chasers and darters are all groups of dragonflies and are well-named after their hunting habits. The damselflies on the other hand are named more after their colours and beauty; emeralds, blues, reds and demoiselles.

At RSPB Fen Drayton Lakes there have been a total of 25 species recorded over the years, making it one of the best places in the east of England to look for them. This includes a few species which are nationally rare or localised but thankfully can be seen with patience at the reserve. One such species is the Norfolk hawker (Aeshna isosceles). As the name suggests, it shouldn’t necessarily be seen in Cambridgeshire, but the species is undergoing an expansion of range and has colonised the reserve in just the last few years. It is a large dragonfly with a uniform brown body and large green eyes. Perhaps the alternative name of green-eyed hawker offers a more practical and appropriate solution.

The best places to look for many of these aerial predators are wetland margins, ideally around ponds, small lakes, slow-flowing rivers and streams. RSPB Fen Drayton Lakes provides a profusion of suitable places to see various species. Two of the best areas to concentrate your efforts include Covell’s Drain, running north from the entrance bridge up to the River Great Ouse and Oxholme Drain, further to the west, alongside Elney and Drayton Lakes. The water in these drains moves very slowly and there are many rushes, irises and other plants for them to perch on. Species to look out for around here include: variable damselfly (Coenagrion pulchellum), a blue and black specialist of the fens; red-eyed damselfly (Erythromma najas), well named as it indeed has large red eyes; and the emperor dragonfly (Anax imperator) with the largest wingspan of any dragonfly in the UK.

Along the margins of the River Great Ouse you will very likely be stopped in your tracks by the gorgeous banded demoiselles (Calopteryx splendens) when they rise up in the air. These are a type of damselfly, and unusually have colour on their wings; in this case a black band running across the wing of the males. In flight the effect is mesmerising. The females, not to be outdone, have a hint of shimmering reddish-gold throughout their wing. If you find a good spot along the river where there is activity, try putting out a finger and one may well land on it providing a close-up view of these fascinating insects.

With 23 species of odonata seen on site this year, and more species possible, why not head out on a sunny day and see what's around?