INSECTS THAT FLY - Part I

The first insects with wings appeared many millions of years ago. Some people think that this happened as long as three hundred million years ago. Among the first flying insects were dragonflies. Some of them were not very different from the dragonflies of today.

Dragonflies have two pairs of wings. These wings move up and down, but they cannot be folded away. The two wings beat together in flight and they do not touch each other. This system of flying works well when the dragonfly is moving in a straight line. However, this system does not work well when the dragonfly has to make a sharp turn. The two wings are then pushed against one another, which makes problems. If you observe dragonflies in flight, you will see that they do not make sharp turns but fly in wide, almost circular movements.
Because of the difficulties caused by two pairs of wings working together, other insects have developed ways of joining their wings together to make one surface.

Bees and wasps use a set of hooks that fasten their front and back wings together when they fly. Butterflies have wings that overlap so that they work as if they were one wing.

Another way of solving the difficulties caused by having two pairs of wings is to reduce the size of the rear wing. Some moths still have a rear wing that hooks on to the front wing, but their rear wing is very small. Flies use only their front wings. Their rear wings have almost disappeared.

And flies are great acrobats in the air, as we all know when we try to swat one which is annoying us. Their extraordinary agility is greatly aided by their vision.

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