iD magazine

CAN DRAGONFLIE­S SEE IN THE RAIN?

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It can hover in place in midair, fly backward, change direction in fractions of a second, and patrol your garden at 40 miles per hour. A dragonfly’s compound eyes, which are made up of 30,000 individual units that contain photorecep­tors, can spot prey at a distance of 130 feet. These eyes are positioned on each side of the insect’s head to afford it a 360- degree field of vision. Dragonflie­s also see more colors than humans. But as soon as that first raindrop hits the ground, all this high-tech equipment no longer does it any good.

Now its potential prey can take a short break. The water droplets that have covered a large part of its multifacet­ed eyes cause a total failure of the optical system. The landscape around the dragonfly becomes blurred, the otherwise highly precise flight paths become muddled. The chance of detection by an enemy is high. At this moment the hotshot aviator is out of commission. But the dragonfly wouldn’t be a dragonfly if nature hadn’t provided some solution to the problem. On the inside of each of its front legs is a row of spiny acanthae used for wiping dirt or water from the eyes during flight. The legs are usually kept tucked away behind its head like windshield wipers and are only folded out when needed.

Unlike adult dragonflie­s, their young, called nymphs, are right at home in the midst of water. In fact they are aquatic for up to the first two years of their lives. During this time before they mature and begin living on land and in the air, they breathe via gills in their rectal chamber.

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