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 larvae breathe by gills, and do not have
spiracles until they are grown up, but all grown-up insects breathe by
spiracles.

Yes, John, the larvae of the dragon flies and May flies breathe with
gills.

I thought you would remember that.

The water boatman breathes by spiracles, and carries his supply of air
with him. All grown-up bugs breathe by spiracles.

Now look down into the pond. I think you will see some water boatmen
anchored near the bottom.

Yes, May, they cling by their front feet. Their hind pair of legs are
rather odd-looking; they have a fringe of hairs on the inside.

John says their hind legs are modified to swim with.

Very good, John.

The hind legs are the oars that row these little boats about in the
water.

But why are the little boats that have come to anchor down there moving
their paddles so constantly?

Ah, yes; it is because they want fresh air to breathe.

You know there is always air in pond water, and they keep their paddles
moving, so as to change the envelope of air that surrounds them.

[Illustration]

They know what to do to take care of themselves, if they _are_ nothing
but little bugs.

When winter comes, they go down to the bottom of the pond and bury
themselves in the mud. They lie there without moving or breathing until
spring, when out they come, as lively as ever.

Yes, certain other animals pass the winter in this way; the bears, for
instance, find a snug den and sleep all through the coldest winter
weather. We call this winter sleep of animals hibernation, and many of
the insects hibernate.

Yes, Ned, hibernating animals can get on with very little air; th