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.
[Ill.u.s.tration: RED RASPBERRY.]
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 gra.s.shoppers make mola.s.ses. 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 c.o.c.kroaches, 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.
[Ill.u.s.tration]
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 quant.i.ty 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.
[Ill.u.s.tration]
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.
[Ill.u.s.tration]
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.