Part 52

The sense of smell, even in the human being, is very wonderful. It is the keenest of all the senses.

You have studied weights and measures, and you know how small a quantity a grain of anything is. Well, you will be astonished to know that your nose can detect the presence of 1/2,760,000,000 of a grain of mercaptan, a substance having a very bad smell.

So you see, insects that can smell very, very much better than we would be greatly influenced by the odors of other insects.

Some of the stink bugs, although so disagreeable if disturbed, are very useful to us, as they eat other insects injurious to vegetation.

Most of them, however, eat fruits and vegetables, and some species do a vast amount of mischief.

THE LOUSE

Yes, John, lice are bugs, and very mean bugs too.

They have lived at the expense of other creatures so long that they cannot exist unless they have a living body to feed on.

Here is a picture of one very much enlarged. No wings, no beauty, a pale white thing, all claws and mouth.

It has a long sucking tube by which it pierces the skin, and a sucking stomach by which it pumps the blood into its mouth.

Such creatures are called parasites.

Yes, bed bugs are parasites too.

Besides the lice that live on human beings, there are species that infest animals.

BIRD LICE AND BOOK LICE

Bird lice are not lice!

That is, they do not belong to the bug order.

They belong to a small order by themselves, but they are parasites like the lice.

The little white book lice that scurry away when we open an old book that has been standing on the back shelf, are not lice, either; they also belong to a little order of their own, and are constructed very differently from the true lice.

FRIEND CICADA

WHIR-R-R-R-RRRRR!!

May says she wishes that locust would keep quiet. It makes her warmer than ever to hear him carrying on so this hot day.

John says it is the weather that is warm, not the song of the locust.

And yet, locusts generally sing during the hottest part of the summer, so that we have learned to associate them with warm weather.

Since we must listen to its shrill out-cry, I wish we could also see it.

Ah, that is a wish soon gratified! Here comes one out of John's pocket.

John says it is not a locust.

Ah, yes, the shorthorned grasshoppers are the real locusts, and this fellow has somehow got the name.

But it is not a locust.