‘Mike, look at this – isn’t it incredible!’ he gabbled, staring intently at a huge dragonfly perched on the end of his finger.
As spring emerges, so will the insect life of our wetlands. Let Mikes blog about a rare encounter with a Dragonfly inspire you…
One of the most rewarding parts of my day job, teaching outdoor education to schoolchildren, is seeing genuine awe and wonder on their faces. Scrambling over and under the huge boulders of West Beck near Goathland can be exciting enough on its own, but last week, one 10-year-old boy from Norton County Primary School made a discovery that took his excitement to another level.
‘Mike, look at this – isn’t it incredible!’ he gabbled, staring intently at a huge dragonfly perched on the end of his finger. And it was. At over 3 inches long, the golden-ringed dragonfly is the longest of its family living in Britain, and fairly common in the North York Moors.
Its habitat of choice is heather moorland, especially where fast-flowing becks are present. These watercourses are nurseries for countless insects – mayflies, stoneflies, blackflies and midges all spending their formative months as underwater larvae. In high summer they hatch and swarm over the water, providing a living larder for predators, golden-ringed dragonflies included. These aerial hunters cruise up and down over the water’s surface, snatching hapless buzzy and flappy things from the air. Once caught, they are dismembered and eaten in flight.
Dragonflies don’t often land or fly slow enough for us to get a decent view of their anatomy or colours, so the individual on Zak’s finger was a rare treat. The reason for its immobility was the fact that it had only just hatched as an adult and was unable to fly. Dragonflies, like the insects that they eat, spend most of their lives underwater then, when fully-grown, crawl out onto beck-side vegetation. Here they split their skin and emerge as winged adults. Before they can take to the air their folded-up wings need to be pumped up and dried, and that was just what Zak’s dragonfly was doing when he found it.
Its body was predominantly black with a series of bright yellow hoops down its tubular abdomen, hence the ‘golden-ringed’ label. Close-up though, the most striking features were the creature’s eyes. They were enormous, like a multi-faceted helmet completely covering the animal’s head. Not surprisingly, dragonflies have superb vision; they need it for spotting prey and manoeuvring at high speed to catch it.
After admiring the new-found insect and taking its photo, we left it on a nearby bush to dry out, ready for its maiden flight later in the day.
As a group of animals insects never reach any great size. Our golden-ringed dragonfly is in fact one of the largest, only an inch behind the giant forest damselfly of South America, which holds the world record for the dragonfly family. What limits insect size is their breathing system. They don’t have lungs or gills, but a series of ventilation tubes called trachea that transport air all over the animal’s body, but this system is only efficient over very short distances. It just doesn’t work in a body over 3 or 4 inches long, and an inch thick.
In the distant past though, the situation was different. 400 million years ago, in the Carboniferous period, our atmosphere contained a higher percentage of oxygen so insect’s breathing systems worked better, and they were able to grow larger. Fossils have been found of dragonflies with a 2 foot wingspan and weighing about a pound. I’m not sure that Zak would have been quite so happy posing for a photograph with a dragonfly the size of a crow on his finger!