Western Morning News (Saturday)
LAST DRAGONS OF SUMMER
Charlie Elder goes in search of dragonflies, and finds our longest and shortest species living side by side
On a warm day this week I walked a path along the westernmost fringe of Dartmoor in search of dragons. The sunshine had coaxed a multitude of insects onto the wing. There were red admiral butterflies aplenty and bumblebees weighing down flowering fronds of heather, while a cloud of craneflies rising from the grass were being targeted by low-flying swallows. Following the stony track beneath the flank of Gibbet Hill I headed for myriad muddy pools that lie at this upland’s outermost edge, fed by rain-fed runnels which carve winding routes through the grass and gorse.
My destination was a stream which emerges part way up the slope from an embankment of exposed peat and runs clear through a shallow gorge, spilling out over the path and into a boggy area beside the old railway line.
This short stretch of water often provides wildlife interest. In the past I have spotted in the pools giant so-called horse leeches several inches long (vegetarians, mercifully) and have often flushed snipe from the marshy banks in winter.
But it was dragonflies I had come to find, and this area is always a promising place to look.
Dragonflies are spectacular insects. Masterful aerial predators, combining agility with an impressive turn of speed, they bring elegance and drama to any stretch of water.
That said, there is something vaguely disconcerting about them, even though they are harmless. Darting around like darning needles, dragonflies watch us with large fencing-mask eyes and don’t seem half as afraid as we might want them to be!
Unnervingly confident in flight, a hovering dragonfly can halt you in your tracks, scrutinising you like a miniature spy craft before zipping away out of sight – doubtless plugging into a secret docking station in order to download its footage. Who exactly is operating these creatures?
Joking aside, they are fascinating and colourful insects and our fifty-plus related kinds of odonata, as their taxonomical grouping is known, can be separated into dragonflies – which are typically robust, powerful fliers that spread their wings at right-angles to the body when at rest; and damselflies – which are characteristically smaller, more dainty and hold their wings together over their back.
Dragonflies are not easy to identify, given there are plenty of lookalike pairings and many species can only be distinguished by small details in their patterning and colour. A few are distinctive enough to be possible to name in flight, but basically it pays to wait until one settles and then take a photograph in order to examine its markings more closely and compare them with illustrations in a field guide, such as the excellent Britain’s Dragonflies by Dave Smallshire and Andy Swash.
On reaching the stream, it didn’t take long before I came across two dragonflies patrolling the flow – engaging in mid-air territorial disputes whenever they met. One of them I was able to identify as it flew back and forth – a large, black individual clearly marked with yellow rings around the abdomen.
This was the magnificent golden-ringed dragonfly.
Mainly found in western Britain, this species breeds in slightly acidic water, so peaty pools on heathland and moorland, such as Dartmoor, are ideal. However, they may also be found hunting far from breeding sites.
They are voracious predators, feeding on any insects they can catch – even smaller dragonflies.
The individual I was watching was actively patrolling his stretch of stream, but I spotted a female resting fairly nearby. The female golden-ringed dragonfly, with a body measuring around 8.5cm, is the longest of all our species and I approached her with stealth to admire her markings and green eyes, and managed to take a photo or two.
For such a fast-moving insect, they are particularly slow when it comes to their life cycle. The aquatic larval stage may last between two to five years. That a long time between her laying eggs and an adult emerging from the water and finally getting airborne.
In general most of the lifespan of dragonflies is spent underwater as larvae. Eggs are laid close to or in water, and the larvae eat live aquatic prey, growing steadily over months or years. When fully grown, larvae climb out and hatch into adults, which then feed up and mature before returning to stretches of water to breed. And mating sees pairs clasped together in a ‘wheel’ – and in some species protective males continue to grasp the female behind the head while she lays her eggs.
The other species I spotted patrolling the stream was a common hawker – another large and robust dragonfly most often seen in late summer in northern and western parts of Britain. It favours acidic upland pools on moorland and heathland and the female has brown and green markings, while the male that I spotted was dark with light blue patterning.
The common hawker is similar looking to the migrant hawker, which flies well into autumn, and the large and inquisitive southern hawker, which will visit garden ponds and likes to hover close to check out humans!
Quite a number of dragonflies are active through September, some into October, and the species I chanced across next, sunbathing on the ground, was a common darter, which can even fly on warm days into December.
Roughly half the length of the golden-ringed dragonfly, this widespread little streak of red commonly basks on bare ground and may be found in a range of watery habitats.
Finally, I noticed a small, dark dragonfly hovering over a thin moss-fringed stream nearby. It was unfamiliar and I managed to get a few photographs once it landed and was delighted to discover it was a new species for me – a black darter.
This declining heathland and moorland specialist shares the shape and restless behaviour of the common darter, but mature males are black, and at around 3cm in length, this darter is also the smallest dragonfly in Britain. I had gone from one extreme – the lengthy golden-ringed dragonfly – to the other.
On my short walk I was pleased to have seen four kinds of dragonfly all in close proximity. They are incredible invertebrates, eye-catching and supremely engineered, the alpha insects at any stretch of water. And they are fun to try to put a name to – especially as they do have such wonderful monikers. So when the sun it out, and you fancy a spot of dragon hunting, go find yourself a darter or a hawker, a skimmer, emperor or a chaser…