NATURE NOTES: The secret life of the autumn dragons
The last day of September was quite a warm and still day and I was sitting quietly near a pond on Druridge Bay watching a pair of dragonflies, locked together in a '˜mating wheel'.
I watched them for over 15 minutes, flying back and forth in tandem along a sheltered glade between the bushes.
Mating like this is unique to dragonflies.
The male grasps the female by the ‘scruff of the neck’ with the claspers at the tip of his abdomen, the female, if she’s interested, will then curl the tip of her abdomen up under the male – this is known as the wheel.
In some species they can stay locked together like this for several hours. Once they are done, the female will go off and lay (or oviposit) her eggs into plants or directly in to the water depending on the species.
The dragonflies I was watching were migrant hawkers Aeshna mixta. They are an autumn speciality in our part of the world, where they can be seen on the wing from August right into October and even early November if it is an exceptionally mild autumn.
Migrant hawkers are a fairly common sight on warm autumn days in Northumberland nowadays but they are a fairly recent arrival to the county with the first one only recorded in 1994 near to the Roman Wall.
The migrant hawker is common across Europe and into North Africa and is found as far east as Japan. As the name suggests, they are migratory and although firmly established as a breeding species in the south of the UK, the number can be hugely swelled with the arrival of immigrants from the continent in late summer.
Migrant hawker is a relativity small member of the hawker family but otherwise it looks similar to many other hawkers, especially the common hawker.
The male is predominantly blue, with spots along the abdomen whilst the female is more brown with similar markings to the male that can be both blue and yellow.
Closer views show a yellow ‘golf tee’ shaped spot on the abdomen which is diagnostic of the species.
Males can often be seen flying low over still water, hovering frequently, looking for females in marginal vegetation.
They can be seen well away from water however, often flying in glades or paths between bushes, both males and females will perch up high but they also bask on lower vegetation.
Dragonflies are in the order Odonata – meaning toothed jaw in ancient Greek, these sharp mandibles are designed to quickly deal with prey which are caught on the wing.
From tiny damselflies to the emperor, Britain’s largest dragonfly, they are both beautiful and an efficient killing machine.
Often brightly coloured, they are masters of flight and manoeuvrability, their strong wings and muscles mean they can travel at up to 36 kilometres an hour.
Another bit of clever design – just like an aeroplane folds up its undercarriage just after take-off, they fold up their front legs and tuck them in behind the eye – amazing creatures!
The majority of a dragonfly’s life is spent in the water as larvae or nymphs which emerge in spring from the egg laid by the female in the autumn.
In the case of our migrant hawkers, where the egg is laid away from the water, the prolarvae wriggles to the safety of the water before moulting into the nymph.
It remains as a nymph, moulting several times as it quickly grows to emerge in the summer. Some species like the golden-ringed dragonfly can remain as nymphs for several years, but the migrant hawker completes the task in a few months.
When it‘s time to emerge, the larvae crawls out of the water and attaches itself to the stem of grasses or rush.
The adult slowly breaks through the larval skin, it then rests to allow the legs to harden before easing its abdomen free and after another hour or so, the wings have hardened enough for it to take its maiden flight.
Life expectancy is short however with most adults dragonflies living for only a couple of weeks or so.
There is still time to see these amazing aerial predators on the wing this autumn.
Choose a warm and preferably still day, afternoons are best and find a sheltered but sunny spot on a path or woodland ride near some water and watch for the males patrolling their patch or perched out on the sunny side of the bushes.
I would recommend Druridge Pools or Hauxley Reserve on Druridge Bay, Howick Gardens, Newton Pool and Embleton Quarry as good places to look for them. But as ever with nature – nothing is guaranteed!
* IAIN ROBSON is the author of the Druridge Diary. Twitter: @ipin_by_the_sea