Five primary veins – costa, subcosta, radius, medius, cubitus and analis – sprout from the backs of dragonflies to create a framework for flight with few peers in the arthropod world. The first terminates at the tip, near which a drop of pigment confers a stabilising weight to each stiff wing. The second ends where the leading edge hits a notch, its duties cut short by the need, perhaps, to strengthen the base of odonate propulsion. The third and fourth veins begin as conjoined twins but soon separate, with the radius giving rise to lines that support the distal margins of the wing and the median fronting a juncture of odd-shaped cells that betray the prehistories of these aerial hunters. The final two wind through the rear, with the anal vein running parallel to the cubital in damselflies but tracing a sock-shaped loop in advanced libellulids.
Zygoterans, save the demoiselles which flutter all wings in laborious synchrony, use a series of counterstrokes to whirl through the slim labyrinths of reedbeds. Dragonflies proper sacrifice manoeuvrability for speed, power and efficiency; save during hovering, when they instantly switch to the rhythms of miniature helicopters, their wings beat in phased sequences to propel hawkers, clubtails, skimmers, dashers and baskers over ponds, lakes and swampy woods. Come dusk, darners erupt from treetop perches to decimate the frontlines of nocturnal swarms; their diurnal kin, the emperors, patrol the margins of still water bodies with relentless purpose, charting a regular route but ready to halt, bank or explode with aeshnid fury should they spy a challenge to their territory.
Duskhawks and duskdarters take over this niche in the dying hours of the day, swaping blue-green giants for swift phantoms that glow with pale fire. One tribe of libellulids has expanded its wingloading and consequently, its range; Pantala and Tramea soar over peaks and even ride oceanic breezes to arrive at isolated lands. Hyaline, coloured or infused with patterns that serve as vivid signals of strength to their own species, the wings of dragonflies repeat and redefine a branch of life that has conquered the open spaces between marsh and mountain to float over cities with room for just a little flight of veinity.
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