D O you think a fly is a very small and common thing? Is it not worth looking at? Let us see about that.
First, here is its head with two great eyes. We will soon look at the eyes. Then you will see how curious they are.
There are, besides the big eyes, three little eyes. These are set on the top of the head. Then, too, on the front of the head we find a trunk or tube. And here is a pair of feelers. Inside the head is the brain, very much like a worm's brain. It is only a tiny white dot.
Next behind the head is the chest. The head has the shape of half of an egg laid sidewise. The chest is nearly square. It is made of three rings.
On the first ring is a pair of legs. On the next ring is a pair of legs and a pair of wings. The fly has only one pair of wings.
On the last ring is a pair of legs. And near these legs are two little clubs covered with fine hair. It is by means of these clubs that the fly can halt or balance on the wing. They help the fly as the second pair of wings helps other insects.
On the Wing
The third part of a fly's body is the largest. It is egg-shaped, and joins the chest by the thick end. This part also is made of rings.
Now let us look at the head of a fly. The feelers are like two long, fine plumes made in joints. Most people think these feelers are made to touch with. Their full, true use is not yet known.
You see, even in a fly there is much left for some of you to find out.
Some people think that flies smell and hear with these "feelers." But then they are so fine that a breath can jar them, and the fly might seem to hear when it only feels.
I know of something else like that. It is this. In some schools for the deaf and dumb, the pupils are called to class or table by rapping on the floor. The deaf do not hear the noise; but they feel the jar, and come as if they could hear.
Let us look at the mouth of the fly. The lip of a fly runs out into a long, slim tube or pipe. With this it sucks up its food.
At the end of this tube is a little flat plate. Close by it are two sharp hairs. These are to prick the food, so that the tube can suck it more easily.
When the fly is not eating, it can shut up this tube like a telescope, to keep it safe. Did you ever see an elephant? Did you see his trunk? The fly's tube is his trunk. The elephant's trunk is his long upper lip. So is the fly's trunk a long lip.
The chief parts to notice in a fly's head are its eyes. These are so large that they make up nearly all the head.
These big bright eyes look as if they had varnish on them. Now each of these eyes is made up of a very great many small eyes. There are four thousand of these small eyes.
Between these two big eyes are three little single
eyes, set in this
Wise men have studied the eyes of flies for many years, and do not yet know all about them.
The wings of a fly have a fine, thin, clear covering. This is held out on a tiny frame, like a network. The fly moves these wings very quickly. The motion of the wings helps to make the sound or buzz of the fly.
Now we come to the legs and feet of our fly. The leg is made in five joints. The foot also has five joints. The last joint of the foot has two claws and a little pad. These are covered with fine hairs.
The hairs catch on little points or rough edges. Thus the fly can walk, as you would say, "upside down," and does not fall. Besides, the pad and hairs act like a sucker. They suck air from under the foot. So they hold the fly from falling as he runs up a pane of glass. All boys know what a "sucker" is and how to make one.