They do _not_ bite, but they pierce with their mouth tubes, and that
feels just as though they bit us. So we commonly speak of bugs as
biting.
If you wish to be very exact, we will hereafter speak of bugs as
piercing or sucking.
Now, Mr. Water Boatman, we are going to have a good look at you.
Nell says it is not like silver any more, but just a little black and
gray speckled bug.
That is because it is now on top of the water. When it goes under it is
surrounded with a layer of air, and that is what makes it look as though
it had on a silver dress.
May wants to know how it manages to take a layer of air down under the
water. If you were to look at it with a magnifying glass, May, you would
see it is covered with fine hairs; the air becomes entangled in these
hairs. Do you not remember how the leaf of the jewel weed, or
touch-me-not, as it is also called, shines when you plunge it in water?
It, too, is covered with fine hairs that hold air. Many leaves shine in
this way when put under water, and always because of the fine hairs
that prevent the air from being pushed out by the water. You see the
hairs on the bugs serve the same purpose as those on the leaves; they
hold fast the air.
Our water boatman breathes this air that surrounds him.
You know how insects breathe do you not?
Dear me, then I shall have to tell you.
They have no lungs; of course, so they cannot breathe with lungs as we
do.
Take a long breath--see how your chest rises--that is because you filled
your lungs full of air.
Well, the insects have to breathe air.
Every living thing has to breathe air. Nothing in the world could live
without air.
Even plants breathe the air, you know.
Now, there is a little row of holes or pores along each side of the
abdomen of the insect.
These are the breathing pores. No, May, the insects do not breathe
through their mouths, they breathe through their sides.
[Illustration]
You can see the breathing pores, or spiracles, as they are called, very
plainly in many insects.
You can see them on the abdomen of the locust, and in some caterpillars
they are bright-colored spots.
There are spiracles on the sides of the thorax, too, but they do not
show so plainly as those on the abdomen.
The spiracles open into air tubes that carry air to the blood of the
insect.
[Illustration: _Spiracles_]
If you watch a grasshopper or a bee, you can plainly see it breathe. The
abdomen moves in the bee as though it were panting. These movements of
the abdomen cause the air to go in and out. All insects move their
abdomens to send the air in and out, but it does not show plainly in all
of them, for, though insects need air, some of them can get along with
very little.
Yes, John, insects have blood. It is not just like our blood, but still
it is blood.
It is not generally red in color, though sometimes it is reddish, and
sometimes it is brown, or violet, or even bright green.
Yes, that seems strange to you, but you remember how ears are ears, and
serve to hear with, no matter where on the body of the creature they are
located. So blood is blood, and serves the purpose of blood, no matter
what its color. The blood of some insects has a very bad odor, and in
the case of certain beetles, when they are disturbed, this foul-smelling
liquid oozes out of the joints of the legs.
Yes, Mabel, it is probably used, like the "molasses" of other little
friends we know, to repel enemies.
But to return to breathing. Some larvæ breathe by gills, and do not have
spiracles until they are grown up, but all grown-up insects breathe by
spiracles.
Yes, John, the larvæ of the dragon flies and May flies breathe with
gills.