Chapter 6
The bad odor comes from a liquid poured out of the back of young bugs, and from the under side of old ones.
These insects are very undesirable acquaintances, and they breed so fast that even one, brought into a house, may cause it to become generally infested in a few weeks.
Eternal vigilance and great cleanliness are the housekeeper's only safeguards.
There are some species of bugs that closely resemble the bed bugs, only they have wings, and live on flowers or in the cracks of the bark of trees.
THE TROUBLESOME RED BUG
There are a great many kinds of bugs on the leaves and flowers in summer, and some of them do much damage by eating the vegetation.
One of the most troublesome of these is the red bug. Here is a picture of one.
Its wings look as if they had an X drawn on them.
Let us spread out one of the wings.
Why do you all laugh?
Sure enough, Ned, how _can_ we spread out the wings of a bug in a picture?
But there is a way out of that difficulty.
Yes, another picture.
Only the upper wings are spread out.
You see, the half of the wing next the body is stiff like a wing cover, and the other half is thin and silky, and folds up under the stiff part. When the insect flies it spreads out the under wings, too, for there is a pair of thin, flying wings folded on the body under these upper wings.
These upper wings, that are half wing cover and half flying wing, are characteristic of the bug order.
Not all the bugs have them, but a great many have.
The name of the bug order is HEM-IP-TERA, meaning half-wing. You see why.
Yes, John, the word "hemiptera" comes from two Greek words, _hemi_, meaning half, and, as you know, _pteron_, meaning a wing.
The young red bugs are like the old ones, excepting in color.
What do we call the young of insects, little Nell?
Yes, we call them larvæ. These red bug larvæ are bright red with black legs.
They pierce the cotton plants in the South, and suck out the juices.
Of course, they grow and moult until they arrive at the adult form.
What, John? You do not know what "adult" means? Adult means "grown-up."
It is a short way of saying grown-up; and after this, when we mean a grown-up insect, let us say an adult insect.
To return to the red bug. When it reaches the adult state, it is not such a bright red, but rather of a reddish color with brownish wings striped with light yellow.
Beside eating the juices of the cotton plants and thus injuring or even killing them, the red bugs stain the white cotton and spoil it.
They are also troublesome in some parts of Florida, where they pierce the skins of the oranges, and cause the fruit to decay.
THE RAVENOUS CHINCH BUGS
There are a great many bugs injurious to vegetation, among them the little chinch bugs.
They are so small, each one no larger than a plant louse, that you would not think they could do much harm.
One of them could not, but when they appear in millions, then they are terrible.
Here is one magnified to show the white wing covers with black markings.
Would you believe that this tiny insect has destroyed millions of dollars' worth of grain in the United States?
What, Charlie? you should think they could be killed out? That is a very difficult task. You see they are so small, and they breed so fast. There are two broods of them in one year, and when they have eaten one grain field they start off, millions strong, to another.
Of course a great many methods have been tried for getting rid of them, and one very curious method you will like to hear about.
You know insects are subject to diseases.
What, Nell, you never heard of a sick bug?
Yet it seems they are sick sometimes, and certain diseases kill them. Chinch bugs are not as healthy in some places as in others.
There is a contagious disease that kills them off in very great numbers.
Ned says he can guess what remedy the people apply to the healthy chinch bugs that are eating their grain.
Yes, they introduce diseased chinch bugs into the grain fields with the healthy ones. The contagion spreads and the bugs die!
There is another way of getting rid of some kinds of troublesome insects. That is, to introduce an insect not injurious to vegetation, that will prey upon the injurious ones.
THE WELL PROTECTED STINK BUG
One of the bugs we know the best and like the least is the stink bug.
It deserves its name.
John says he had one on his hand this morning.
How did you like it, John?
Did any of you ever pick berries where these bugs were?
See what a face Mollie is making! It is very evident that _she_ has.
What a nasty taste they give the delicious fruit.
Even the flavor of the red raspberry is spoiled if one of these bugs pollutes it.
What makes them smell so? May is asking.
The disgusting odor is caused by a liquid that is ejected out of little pores on the under side of the thorax.
The bug can eject this liquid when it pleases.
Most members of the bug order can eject a disagreeable liquid, though few of them do it so successfully as the stink bug.
If the stink bug is not disturbed, it does not give forth the bad odor; but when we jostle the bushes in getting the berries, that startles it, and we get the benefit of its alarm.
Yes, undoubtedly the bugs make a bad odor for the same reason the grasshoppers make molasses. They wish to repel their enemies.
Very few birds ever touch a stink bug.
Nell thinks a bird would be crazy to eat a stink bug.
Mollie says if it were not crazy when it began, it surely would be before it got through!
Not only the bugs make these disagreeable odors.
Many other insects do.
The cockroaches, as we know, and one reason we dislike them so is because of this offensive odor.
Some species of crickets, too, and indeed many, many insects give forth odors from glands that exist just for that purpose.
No, indeed, these odors are not all alike. Some have a strangling quality like ammonia, and sometimes the odors are not disagreeable. Some insects have sweet odors, like perfumes.
The pleasant odors are not used to repel, but to attract.
If an insect wishes to see its mate, it may be able to give forth a pleasant odor that will reach a long way through the air, and the mate, smelling it, will follow it to its source. You see, this pleasant odor is one way of talking; at least it is one way of sending a message.
Insects can detect odors much better than we can.
No doubt many insects produce odors that affect other insects, but that are so faint we cannot smell them at all.
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.
It is also called the dog-day harvest fly, but it is not a fly, though it looks considerably like one.
Really, you know, it is a--bug!
Yes, it belongs to the bug order.
Its true name is cicada, and its shrill midsummer song has been famous from the beginning of time.
It looks like an enormous fly, but its mouth parts are the mouth parts of the bug, and in other respects it resembles the members of the bug order, when it is examined closely.
What glassy wings!
Let us spread them out carefully. Four of them it has.
The cicada, you see, has no wing covers. Nor are its upper wings, half wing cover, and half wing, like those of so many of the bugs.
No, all four of its wings are alike, and all four are flying wings.
When it is at rest, the inner wings slip out of sight under the outer ones, which fold down like a roof over its body.
See how beautifully the wings, are veined.
You think cicada has a very broad back, Nell?
So it has, and a broad head.
See its black eyes on the corners of its head!
How many facets have its eyes?
I wish I knew, but I do not. This, however, I can tell you. If you look on the top of its head between its compound eyes, with a magnifying glass, you will find it has three little eyes there.
These small eyes are simple, and are called _ocelli_.
Many insects have ocelli, indeed, some of the grasshoppers have these extra eyes on top of their head.
May says the grasshoppers are very astonishing insects.
You think you know all about them, and you are all the time finding out something new. You would not be apt to notice these little ocelli on the grasshopper's head, they are so small, and besides, some of the grasshoppers do not have them.
Yes, Mollie, it is the same with the crickets and katydids. Some species have ocelli, and some have not.
If you look full in the face of a cicada, you can see the three little round ocelli between the compound eyes.
They show very plainly with a magnifying glass.
Indeed, it is difficult to explain what the ocelli are for.
Some think they are to see objects close at hand, while the compound eyes see more distant objects.
Others think the ocelli are only capable of distinguishing light from darkness.
Yet others think they are merely a "survival" of the eyes of the worms. You know, way back in time, before there were winged insects there were worms. In some way the insects are descended from the worms, and though they have got rid of many of their wormlike parts they still retain some of them, and probably among these are the ocelli.
When an animal of any kind keeps organs that belonged to its ancestors, but that are of no use to it, we say these organs are "survivals." They have not yet had time wholly to disappear.
Yes, John, the time may come when the ocelli will disappear from the insects. A good many insects have lost them already.
Indeed, you are right, May; they have lost them because they did not use them. When an animal ceases to use an organ in course of time, for lack of exercise, that organ dwindles away and disappears. It generally takes a very long time for this to happen.
Yes, Mabel, thousands or even millions of years may pass before an organ that has gone out of use entirely disappears. As generations succeed each other each generation loses a little power in that organ until, finally, there is no organ left.
John is puzzled to know just what is meant by an organ. It is some particular part of the creature. An arm is an organ, a stomach is an organ, an eye is an organ. The whole creature is made up of organs, and is called an _organism_.
Your whole body, John, is an organism, but your legs and arms are organs. Now, I think you understand.
Our cicada has one organ that is very interesting; it is the little apparatus by which it sings.
Turn it over, Ned, and all of you look at the two thin plates lying against the abdomen just below the thorax.
Those membranes are like two little kettle drums, and they are its song organs.
There are other membranes beneath them, and large muscles within the body to move the membranes.
The membranes being set in rapid vibration we get the shrill cry of the locust.
Only the male has the kettle drums. In the female these organs are rudimentary, and she is dumb.
Cicada, you are a pretty little thing with your clear, glasslike wings and your black body with red and green trimming. See its mouth lying in that little groove under its head. It is a tube, and sharp. The cicada sticks it into a leaf or young twig to suck out the juice.
Nell wants to know if the young cicadas are like the old ones. Indeed, they would be cunning little things if they were, and--yes, they _would_ look very much like flies.
But the young cicadas are queer babies, indeed. They do not look very much like their parents, although they have a head, a thorax, and an abdomen.
The female cicada makes a slit in the bark of the tree twig with her ovipositor and lays the eggs there. As soon as they hatch out, the tiny cicadas drop down to the ground and burrow into the earth.
You would not know that they are cicadas, they are such queer-looking little things. But they have strong, sucking mouth parts with which they pierce holes in the roots of trees and suck out the juices.
Of course these larvæ grow and moult and continue to do so until they have moulted a good many times and grown quite large.
They stay down under the ground two years.
At the end of that time they crawl up to the surface of the earth in the early summer.
They climb trees, or weeds, or fence posts, and then the skin splits down the back for the last time, and out comes a full-grown cicada with bright glassy wings.
The wings of the larva do not grow at each moult like the wings of the grasshopper.
The larva never gets beyond short little wing pads. See John's eyes twinkling! I believe--yes, he has! He has brought us the cast-off skin of a cicada to look at.
Why, John, you are like a good fairy to us to-day, giving us just the things we want just when we want them.
Now, see this little shell. See the front legs, like strong paws to dig with. And see its little glassy eyes, and its little wing pads!
It is a perfect cast of the cicada larva.
Yes, May, this little cast is made of chitin, and it will last a long time. Chitin is a very indestructible substance; even fire will not destroy it, but in course of time the moisture and the acids in the earth destroy it, so that at last the millions of cicada shells and grasshopper cast-off skins, which are also of chitin, and cricket moults, and all the other little cast-aside chitinous overcoats of the insects, return again to the earth and the air whence they came. The minerals and gases that compose them let go of each other, as it were, and the chitin is no longer chitin.
Amy says she has seen these little cicada shells hundreds of times but did not know what they were.
Yes, we are sure to find them almost every summer.
If we look, we will also find other larvæ shells. Down in the grass are the cast-off coats of the grasshoppers and the crickets.
All we need do is to look, and we shall be sure to find them--like unsubstantial ghosts of the active little wearers.
No doubt you all have heard of the seventeen-year locusts. They, too, are cicadas, and they look very much like this one, only it takes the young ones seventeen years to complete their growth.
Think of living in the ground and sucking the juices out of the earth and of tree roots for seventeen years!
How would you like to do it?
But no doubt the cicada is quite happy living in this way.
At the end of seventeen years the cicadas come up out of the earth in great swarms.
They cast their skins for the last time. The queer little shells are seen everywhere, and the air resounds with the songs of the freed prisoners.
In the South it takes only thirteen years for these cicadas to develop.
I once went up the side of a beautiful mountain in North Carolina, where was such a mighty host of cicadas in the trees that I could not hear my companion speak, and a little way off the noise sounded like a torrent of rushing water.
THE ODD SPITTLE INSECT
Why, little Nell! What is the matter?
You do wish the frogs would stop spitting on the grass?
Let me see; why, poor child, she is all covered with frog spittle.
That is kind, Ned. See, he is wiping her apron off with some fresh, clean leaves. Let us rest awhile under this shady tree.
John, pick that grass blade with the frog spittle on it. Be careful not to disturb it.
There is a surprise in store for you; this white frothy substance that is so abundant in some places in the summer and that looks like spittle is--guess what?
Frog spittle, May says. So you think the frogs spit on the grass do you? They must be tall frogs to reach up so high.
With this little twig let us carefully brush away the white froth.
Now see.
Yes, there is something in the centre of it.
It is the larva of a--bug!
The female bug, and here is one of the little things, lays the egg on the leaf or twigs, and when it hatches the young bug sucks out the sap of the plant which finally appears as this white froth.
The larva remains surrounded by the froth until its transformations are complete.
Just before the last moult it stops sucking out sap. The froth dries about it in the form of a little room, and in this it undergoes its last moult and comes out--an adult bug.
The froth is supposed to be used as a protection, and it may be against some enemies, but there are certain wasps that delight in invading the frothy masses and hauling out the unwilling morsels within to feed to their young.
No, little Nell, the frogs have nothing whatever to do with this frothy substance which was called frog spittle before people understood about the little insect that made it.
They really thought the frogs did it.
The adult spittle insect is called a frog hopper, and it has the power of leaping very well.
PRETTY LEAF HOPPERS
Just see this bush! Be careful not to shake it.
It is covered with such pretty, bright-colored little insects.
There, May ran against the bush and see--they are hopping wildly off in every direction.
Yes, little Nell, they do sound like rain drops pattering on the leaves.
They are prettier than the spittle insects and more slender, but they hop about in very much the same way.
The larvæ do not make froth, however.
These are the leaf hoppers.
What big heads they have!
And how daintily their green forms are pencilled with red lines.
There are a great many species of the leaf hoppers, and not all of them are as pretty as these.
Some of them are very small indeed, and some do great damage to the grain crops and the fruits.
They suck out the juices of the plants.
If you sweep the insect net over bushes or through the grass in midsummer, you will be pretty sure to draw in a good collection of leaf hoppers.
Most of us are only too well acquainted with the rose-leaf hopper that swarms on rose bushes and kills the leaves. If we have not noticed the insect itself, we have not failed to notice the little white skins that it has cast off and left clinging to the leaves.
Yes, these are the little skins it discards when it moults.
John says we can kill them by washing the bushes with strong soap suds.
Ned says it is better yet to spray them.
It is better and also easier to spray them than to wash them.
You know there are machines for spraying trees and other plants. They consist of a tank to hold the liquid that is to be sprayed and a pump to force it through a rubber pipe with a sprinkler at the end.
Very often a mixture of soap and kerosene oil, known as "kerosene emulsion," is used to spray with.
Paris green and blue vitriol, both very poisonous, are often used on grape vines before the grapes are formed, and very gaudy vines they are for a little while after this bright poison has been sprayed upon them.
Although insects are so very interesting, we have to protect ourselves against many species in order to live.
Yes, John, it is oftentimes merely a question which shall profit by the crops we plant, the insects or ourselves.
Sometimes the insects win, sometimes we win, but it is a closely contested warfare all the time.
We plough the land and take care of it, we plant the seeds and keep out the weeds. Then, when we have a fine crop growing, along come certain destructive insects, feeling very happy, no doubt, to have found such a feast.
Now the fight begins. They attack the crop, we attack them. We spray them with poisons, burn up their eggs, do everything we know how to get rid of them.
Wise men have spent many years of close study finding out the habits of the insects destructive to grains and fruits, in order to be able to destroy them.
Although many of the plant hoppers are such nuisances to us, there is one family of hoppers that is seldom a nuisance.
THE COMICAL TREE HOPPERS
Do you know the tree hoppers,--absurd little jokers that they are?
Oh, yes, they are hard and three cornered, like animated beechnuts, as somebody has said.
Yes, some of them have humps on their backs and some have horns.
John says he once made a collection of tree hoppers and put them in a box with a reading glass over the top, and showed them to his friends to make them laugh.
May says she saw them, and they reminded her of Brownies.
Would it not be fun to have a tree hopper Brownie book!
The tree hoppers jump about on the bushes and eat the juices of the plants, but there are not usually enough of them to do damage. They seldom come in swarms like some of the leaf hoppers, though sometimes they do.
THE JUMPING PLANT LICE
The jumping plant lice are nearly related to the tree hoppers, but they do not look at all like them.
Under the magnifying glass they look like tiny cicadas.
See, here is a picture of one enlarged.
Their natural size is no larger than a plant louse.
Have you not often seen them clustered close together on the young twigs of pear trees--tiny, light-colored things that jumped in all directions when you touched the twig?
The name of the plant louse that infests pear trees is the pear-tree psylla. It is very destructive to pear trees, sucking out the juices of the young shoots.
The pear trees can be saved by spraying them with kerosene emulsion as soon as the young leaves have opened in the spring.
THE APHIDS
Now, let us go in search of the aphids, or aphides, as they are also called. We shall not have to search far.
In a very dry season we generally need not search at all. All we need do is to examine the nearest weed to find plenty of aphides.