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 way—
Wise men have studied the eyes of flies for many years, and do not yet know all about them.