In Flight
The dragonfly that you recognize flitting over fields looks very different from its nymph form. The male dragonfly’s black body is about 70 millimeters (2.8 inches) long and dotted with dashes of apple green and turquoise. Its bright colors are designed to attract a mate. Its two sets of wings stretch out nearly 110 millimeters (4.3 inches) from its body.
This male southern hawker dragonfly is in flight.
An adult southern hawker's eyes have thousands of lenses.
In the insect world, the dragonfly’s sight is unmatched. Its two compound eyes are made up of thousands of individual lenses. The front of each eye is dedicated to forward flight. The top of each eye searches for prey.
In addition to the compound eyes, dragonflies have three simple eyes. Each consists of a single lens. These eyes form a triangle on the top of the head between the compound eyes. Nerves connect these eyes directly to the dragonfly’s flight muscles. They give information about the dragonfly’s relative position to prey.
Like other dragonflies, the southern hawker uses its two sets of wings to fly forward, backward, and sideways. It can swoop, hover, and soar. It can beat its wings together or move each one separately. To fly, the wings twist in a figure-eight motion.
Having two sets of wings means the dragonfly doesn’t have to work as hard as some insects to keep itself airborne. For the southern hawker, that’s about 30 beats a second. For the average mosquito, it’s more like 800 beats a second. It might take the southern hawker less effort, but it can certainly fly fast—up to 54 kilometers
(34 miles) an hour.
Dragonflies have six legs, but most cannot walk.
This southern hawker is on the hunt for flying insects.
Focused Hunter
When the southern hawker hunts, it becomes a deadly predator. A dragonfly’s success rate is about 95 percent. Compare that to other top predators like lions—at 25 percent—and you can see how successful this insect is.
All prey is caught and eaten “on the wing,” meaning while the dragonfly is in flight. The ability to intercept prey while flying at top speeds is a complicated process.
Since both predator and prey are moving, the dragonfly has to be able to predict where the prey will be in order to catch it. To do so, it must calculate three things: the distance to its prey; the direction the prey is moving; and the speed that it is flying. In the span of milliseconds, the dragonfly plots its course.
The dragonfly holds its legs forward, just under its jaw, to form a basket. It scoops up the prey. The long spines on its legs grip the prey. The dragonfly bites off and discards the prey’s wings before eating its body. Dragonflies can eat hundreds of insects in a day.
Eating and mating are an adult southern hawker’s only two jobs. The females quickly lay their eggs. Within two months, the southern hawker adults die. Their eggs are waiting, though, for the life cycle to begin again.
Females lay their eggs in the water.
