Animal Magnetism The Dragon Flies

Situated in the Jura mountains of western Switzerland, it's only appropriate some of Fourmilab's fauna be totally Jurassic. (When I installed the first Sun workstation here, I named it “Jurassic SPARC”.) No dinosaurs here (boo hoo!), but every summer the Fourmilab pond is patrolled by a creature which would be entirely at home when giants trod the Jura. I was looking at the pond one day in July 2003 when I noticed this huge (about 5 cm long), bizarre-looking bug on the bottom of an unfurling lily pad. It turned out to be a dragonfly nymph. (I'm neither an etymologist nor an entomologist, but this sure isn't my idea of a nymph!)

Dragonflies lay eggs in the pond water which hatch into larvæ which repeatedly moult (shed their exoskeletons) as they grow. The larva's final moult transforms it into a nymph, a voracious aquatic predator. If you handle one carelessly, it can deal you a nasty bite—in fact, their biological order, Odonata, is derived from the Greek word for “tooth”. Eventually, the nymph crawls out of the water, fixes itself to an object, then emerges as an adult dragonfly which bursts, Alien style, from the back of the nymph, which remains as an empty husk until something dislodges it. That's what's happened here: the dragonfly had dragonflown away before I arrived upon the scene, leaving behind the nymph's shell with squiggly bits where it burst out.

Having seen the nymph, there was every reason to expect to soon spot the adult dragonfly patrolling the pond and indeed, the next day, there it was. These large dragonflies, unlike the little blue ones, rarely alight: they remain in near constant motion, hovering occasionally. As befits a real world bug-eyed monster, their vision is acute, and they feed on flying insects which they catch in mid-air. Their appetite (consider the energy they expend in flight) accounts, in part, for the paucity of mosquitoes in the environs of Fourmilab. Their almost incessant motion, rapidly beating wings, and random flight path makes them difficult to catch, whether you're a bird looking for lunch or a photographer bent on bug portraiture. I've found the best approach is to observe the dragonfly patrolling the pond for some time, taking note of the areas where it's prone to hover momentarily. Choose one of these with a background against which the dragonfly will stand out then, camera at the ready, stalk the wild dragonfly—wait for it to come to you, then shoot if and when it does.

Photographically, this is one of those situations where you “want it all now”—a small aperture for maximum depth of field (since you can't predict how far from the lens the dragonfly will eventually hover), a fast shutter speed to freeze the rapidly-moving wings, and slow, fine-grained film (or the equivalent in digital sensor integration time) for the sharpest image, since the the insect will appear relatively small in the frame. This makes direct sunlight the best illumination for photographic attempts which is fine, since that's when the dragonfly is most likely to be active. Given all the constraints, it's unlikely you'll be able to use a shutter speed fast enough to freeze the motion of the wings. The image above just happened to be taken near the moment the insect's wings are stationary, reversing direction from upward to downward motion. This isn't something you can plan for, but patience and perseverance ultimately pay off.

This is a Southern Hawker Dragonfly (Aeshna cyanea). They are common throughout Europe at altitudes up to 1000 metres. Fourmilab, at 806 metres, is toward the top of this range. This is one big bug, but nothing compared to the fossil dragonfly Meganeura monyi which flourished about 300 million years ago and had a wingspan in the vicinity of 70 centimetres! While dragonflies shared the Earth with the dinosaurs, they came on the scene about 100 million years before the first dinosaurs. They are the first flying insects found in the fossil record and, little changed today, remain among the most primitive. Unlike almost all other present-day flying insects, they cannot fold their wings back against the body—they are permanently extended.

Just a few hours after I photographed the dragonfly on the wing, I'd opened up the door to the Fourmilab high bay getting ready to take the rubbish out when I heard an almost metallic buzzing from the vicinity of the door. While I wasn't looking, the giant dragonfly had flown into the high bay and then, attempting to leave, become trapped between a sunshade and the window in the high bay door! Before I did my good deed for the day, I took advantage of this rare opportunity to see one not in motion and take this shot showing just how big they are. This one is about 7 cm long with a wingspan of 10 cm. Hardly Meganeura, but big enough for me! I removed the sunshade and the dragonfly flew away, none the worse for the experience.

The photo of the dragonfly nymph was taken by John Walker on July 13th, 2003 with an Olympus C-3040 digital camera in macro zoom mode with an auxiliary 1.45× teleconverter. Focus was manual, using the LCD screen on the camera as a reflex viewer; exposure was f/4.5 at 1/100 second. I'd have preferred a smaller aperture, but illumination was skylight with the Sun already set behind the Jura, and with the lily pad swaying in the breeze, 1/100 was the shortest shutter speed I judged tolerable. The picture of the dragonfly on the wing was taken on July 15th, 2003 with the same camera at maximum zoom with automatic focus (spot mode), and exposure. Catching one of these creatures in flight is a matter of patience and luck. This is the best of more than 75 attempts, a large majority of which failed to even catch the dragonfly in the frame. At least with a digital camera you needn't feel guilty about wasting film! The shot of the trapped dragonfly was taken later the same day, also in all-automatic mode. The Sun had set shortly before and illumination was diffuse northern skylight, accounting for the blue cast and subdued colours. Here I've opted to show what my eye and camera saw rather than manipulating the image to make it look like something it's not.

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