Pets: Why we’re fall­ing for the low-rise dachs­hund

Dr Ben Ald­iss looks at the re­mark­able life of th­ese air­borne preda­tors

EDP Norfolk - - INSIDE - Dr Ben Ald­iss wildlife jour­nal­ist and broad­caster, deputy man­ag­ing ed­i­tor of World Agri­cul­ture Dr Ben Ald­iss is a wildlife jour­nal­ist and broad­caster, deputy man­ag­ing ed­i­tor of World Agri­cul­ture and an ad­viser in bio­di­ver­sity and ed­u­ca­tion on farms. wasp

Hav­ing combed the un­der­growth for cater­pil­lars in last month’s look at Nor­folk’s na­ture, we’re still hunt­ing in­sects in Septem­ber. This time it’s D for Drag­on­flies and I’m pre­dict­ing an abun­dance of them around then. I say ‘pre­dict­ing’ be­cause I’m writ­ing this a full six weeks early to meet the nec­es­sary pub­lish­ing dead­lines. If we con­tinue to ex­pe­ri­ence the won­der­ful sum­mer weather I’m look­ing at through my of­fice win­dow, then the sea­son of many in­sects – in­clud­ing drag­on­flies – will be ex­tended and their num­bers will in­crease as well.

Drag­on­flies re­ceived their name at least 400 years ago and it aptly de­scribes the be­hav­iour of the larger ones as they dash through the air on their strong wings in search of prey. We have around 25 species in Nor­folk, a num­ber of which are still on the wing in Septem­ber.

The smaller va­ri­eties may look less im­pres­sive at first glance, but their colours can be equally stunning, if not more so. Th­ese smaller ones are the fa­mil­iar dam­sel­flies, in­clud­ing the com­mon Azure Dam­selfly with its bright blue ab­domen and a par­tic­u­larly jewel-like crea­ture called the Banded De­moi­selle, the male of which is un­mis­take­able as he dances up and down over the wa­ter in his

liv­ery of irides­cent ul­tra­ma­rine with dusky patches on each of his four wings.

Not only are dam­sel­flies smaller than their huge cousins, but they dif­fer in their weak, flut­ter­ing flight, their rel­a­tively small eyes and the way they hold their wings at rest: folded par­al­lel to their bod­ies as op­posed to stretched out flat at right an­gles.

I’m go­ing to write about other Nor­folk spe­cial­i­ties un­der the let­ter N, but one should log­i­cally be in­cluded here – the Nor­folk Hawker Drag­on­fly. This im­pres­sive crea­ture is large and quite colour­ful, be­ing mainly a light tan colour with yel­low mark­ings and enor­mous green eyes. If you were lucky, you might have seen one dur­ing its rel­a­tively short sea­son in June and July, hunt­ing around its favoured habi­tat in and around the Broads.

Nor­folk Hawk­ers – like all drag­on­flies and dam­sel­flies – are car­ni­vores, but the fe­male of this species seems to de­pend on a rare plant, the wa­ter sol­dier, in which to lay her eggs.

The eggs of drag­on­flies and dam­sel­flies hatch into nymphs, but but­ter­flies and most other in­sects pro­duce lar­vae, the dif­fer­ence be­ing that nymphs re­sem­ble minia­ture adults, whereas lar­vae are com­pletely un­like their par­ents (just think of a but­ter­fly cater­pil­lar or fly mag­got). Drag­on­flies share this fea­ture of their life cy­cle with grasshop­pers and cock­roaches – a young grasshop­per looks like a tiny ver­sion of the adult.

Drag­on­fly and dam­selfly nymphs have six legs and big eyes, but only de­velop wings when they emerge from the wa­ter and crawl out of their fi­nal skin to be­come an adult. The smaller dam­sel­flies spend a year or less as nymphs, chang­ing their skins only a few times as they grow.

The Nor­folk Hawker and other drag­on­flies though, have to un­dergo this ecd­y­sis, as it’s prop­erly called, around 15 times over the course of the two or three years they spend un­der the wa­ter. When near­ing ma­tu­rity, drag­on­fly nymphs are big, fear­some-look­ing beasts, but even then they rely on cam­ou­flage to avoid be­com­ing fish-food and also so they can creep up on their prey.

The Nor­folk Hawker nymph is pre­dom­i­nantly pale brown with darker speck­les, al­low­ing it to blend in very ef­fec­tively against the muddy bot­tom of the pond or broad. It will eat any small crea­ture it can catch, in­clud­ing tad­poles and young frogs.

Con­sid­er­ing the im­pres­sive speed of its par­ents in flight, the nymph is a very slug­gish crea­ture, so it would seem to have trou­ble cap­tur­ing its prey, or es­cap­ing preda­tors. How­ever, it has two re­mark­able adap­ta­tions.

If it needs to es­cape, it can use a form of jet-propul­sion by squirt­ing wa­ter forcibly out of its back end, send­ing it shoot­ing for­wards out of dan­ger. Then, if it’s hun­gry, it has an­other as­ton­ish­ing trick. Creep­ing up slowly to within a cou­ple of cen­time­tres of its prey, it sud­denly shoots out a tele­scopic, hinged jaw from be­neath its head.

Called a mask, this use­ful at­tach­ment has two claws on the end that grip the un­for­tu­nate prey be­fore drag­ging it quickly back to the mouth. Dam­selfly nymphs also have this fea­ture for cap­tur­ing prey, but in­stead of the jet-propul­sion ap­pa­ra­tus, they carry three leaf-like gills at the end of the ab­domen and es­cape preda­tors by sin­u­ous move­ments of their bod­ies, us­ing their gills like the fins of a fish to pro­pel them through the wa­ter.

When ready to emerge as an adult, the nymph crawls up a plant stem out of the wa­ter that’s been its home for so many months, then emerges as a winged drag­on­fly or dam­selfly a few hours later by split­ting its fi­nal nymphal skin. Un­like other in­sects, though, adult drag­on­flies don’t de­velop their fi­nal colours un­til up to a fort­night af­ter emerg­ing and will spend most of this time hunt­ing some con­sid­er­able dis­tance from their pond, be­fore re­turn­ing, re­splen­dent in their daz­zling liv­ery to hunt over the wa­ter where they spent their youth.

The Nor­folk Hawker will eat any small crea­ture it can catch, in­clud­ing tad­poles and young frogs

ABOVE: A Nor­folk hawker drag­on­fly at Up­ton Fen

ABOVE: De­moi­selle by the river Yare at Baw­burgh

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