Identifying British Dragonflies and Damselflies by the Water

There are few better ways to spend a warm afternoon than standing on a riverbank watching dragonflies quarter the water. Britain has around forty breeding species, and a slow lowland river with a meadow behind it will show you a good share of them between May and September. The key is knowing what to look at first, because the difference between a hawker and a darter is not a matter of luck — it is a matter of eyes, wings and posture.

Damselfly or Dragonfly? Start With the Eyes

The single most reliable split, and the one to teach yourself before anything else, is the eyes. On a dragonfly the eyes are large and meet on top of the head, giving the face a broad, helmeted look. On a damselfly they sit clearly apart, like two beads at either end of a narrow head. This works at almost any angle and in dull light, which matters when your subject is patrolling a willow twenty feet away.

• Damselflies are slender and fine, with a long, thin abdomen and wings that narrow sharply at the base. Most settle with the wings folded along the back, so a resting blue damselfly looks like a neat splinter of colour on a leaf.
• Dragonflies are heavier and more powerful, with wings broad at the base and a thicker thorax. They perch with the wings held out or slightly forward, and their flight has an unmistakable purpose about it.

The exception worth memorising is the demoiselles. The banded demoiselle and the beautiful demoiselle are damselflies, but they perch with wings half-spread and flutter like butterflies. A male banded demoiselle — metallic blue-green with a dark thumbprint on each wing — bouncing along a slow river is one of the great sights of an English summer.

Watch the Posture, Not Just the Colour

Once you have decided you are looking at a dragonfly, watch what it is doing with its body. Hawkers are restless and patrol long stretches of bank, rarely settling for more than a few seconds. Darters perch low on stones, bare earth or fence posts, dart out to snatch a fly and return to the same spot. Chasers sit boldly on top of reeds and iris heads, launching upward at passing prey.

The emerald damselfly is another that holds its wings partly open at rest, and its metallic green body makes it hard to confuse with anything else. Colonial and often found at shallow, grassy pools beside rivers, it rewards a careful look.

Sorting the Dragonflies: Hawkers, Darters and Chasers

Wing shape gives the game away once you are practised. A hawker's wings are long and narrow, like a glider's, and sit well clear of the abdomen when at rest. A darter's wings look shorter and broader in proportion to the body, and a chaser's are broader still, with a dark patch near the base.

• Hawkers — the emperor, southern hawker, migrant hawker, brown hawker and golden-ringed. The emperor is large and blue-green and defends a territory over open water. The southern hawker is dark with green and blue spots and will often hover close to people. The brown hawker has amber-tinted wings and flies late into the evening. The golden-ringed, with bold black and yellow banding, belongs to upland streams.
• Darters — common darter and ruddy darter are the two you will meet most often. Look at the legs: dark on the common darter, black on the ruddy, whose males also show a pinched, waisted abdomen and a deep blood-red body. The black darter turns up on heathland pools rather than rivers.
• Chasers — the four-spotted chaser has a dark spot on each wing and flies over still margins; the broad-bodied chaser is unmistakably flattened and broad, with a powdery blue body in males.

Timing Your Visit: A Rough Flight Season

Seasons overlap heavily, but a rough calendar keeps your expectations sensible and helps confirm an identification long after the fact.

• April and May — the large red damselfly is usually first out, followed by the banded demoiselle from mid-May.
• June and July — the peak. Azure and blue-tailed damselflies crowd the marginal plants, emperors patrol, four-spotted chasers and golden-ringed dragonflies appear on their respective waters.
• August — southern and migrant hawkers are everywhere, ruddy darters join the common darters, and evenings become the best time to look.
• September and October — common darters linger, sometimes into November in mild years, while migrant hawkers persist late.

Weather matters as much as date. Warm, still, bright conditions with a little broken cloud are ideal; strong wind keeps everything low in the vegetation, and heavy overcast sends most species to roost.

Practising Well on the Bank

Choose a stretch where a meadow meets the water and walk it slowly, stopping often. Sit still for twenty minutes somewhere with a good view, and let the insects come to you. Carry close-focusing binoculars, a notebook and a pencil rather than relying on photographs alone — noting the date, the weather, the habitat and the perch will teach you more than a blurry image ever will.

Approach settled individuals from the side, moving in short, slow steps, and resist the urge to chase patrolling hawkers; they will usually come back along the same line within a minute or two. Look along vegetation at chest height for resting damselflies, and check bare ground and stones near the water's edge for darters. Never handle a dragonfly or disturb a pair that is egg-laying, and keep dogs and children clear of the marginal plants, which hold the nymphs that will emerge next spring. Do this patiently for a single season and you will find you can name most of what you see before it lands.