Insects are very neat little folks.
They are always cleaning their wings and their legs and their antennæ
and their bodies.
The spines on their legs are very convenient for that.
Charlie says he thinks the grasshopper's legs are as good as a whole box
of tools.
So they are, and you have not yet heard all they can do.
The funniest is to come.
Mr. Grasshopper sings his song with his hind legs!
He rubs the inside of his femurs against the outside of his wings.
There is a row of very fine spines down the inside of the femur for the
use of the little fiddler.
He scrapes away with these on his wing covers.
Yes, Ned, his femur is his violin bow, and his wing cover is his violin.
The noise he makes does not sound much like a violin, little Nell
thinks.
No, indeed, it does not.
It is the shrilling sound we hear in the grass in the summer time.
[Illustration]
It is only the male grasshopper that sings.
The little lady grasshopper sits still and listens to him.
Now, let us look at the other legs.
The front pair are the smallest.
Can you find the little coxa and trochanter?
Yes, Charlie, we will draw the little front leg.
Let us number the segments as we did those of the hind leg.
See, the femur is larger than the other segments, but it is small as
compared to the femur of the hind leg.
The tibia is shorter, too, than the tibia of the hind leg.
The little tarsus is like the tarsus of the hind leg with its claws and
its pulvillus, only, of course, it is smaller.
The middle pair of legs is like the front pair, only larger.
Now, see how the legs are placed on the grasshopper's body.
[Illustration]
The front pair are directed forward. When the insect walks, they pull.
The middle and hind legs are directed backward. When the insect walks,
they push.
Well, little legs, you all have your own work to do, and you surely do
it very well.
Let me see, who has front legs as odd as the grasshopper's hind legs.
Yes, Mollie, the mantis has.
Let us look again at the mantis.
Here is another picture of it.
Its hind legs are just common walking legs, you see.
And so are its middle legs.
[Illustration]
John says they are directed forward instead of backward.
You can see why.
They have to take the place of the front legs, that do not touch the
ground at all.
They have to hold Mr. Mantis up, and pull him along when he wants to
walk.
Now, let us see if we can make anything out of these front legs.
The coxa is small and close to the body.
The trochanter, II, is very large and long.
Yes, Charlie, it increases the size and strength of the leg very
greatly, by being thus enlarged.
The femur, III, is large and strong, too, and it has a row of sharp,
spiny teeth down the inside.
The tibia, IV, is also well supplied with cruel teeth, and at the end of
it is the tarsus, as you see.
You know how the mantis uses these legs. The joint between the tibia and
femur is a strong hinge joint. If can shut the tibia close to the femur,
the spiny teeth of the one locking into the spiny teeth of the other,
and forming a terrible trap for the insects that are so unfortunate as
to get caught in its merciless grip.
Altogether, you see, it is quite a terrible leg, though it has no more
segments than a common leg.
The segments are changed in shape and size from the regular leg
segments.
When any part is changed from the regular shape or size, we say it is
_modified_.
The front legs of the mantis are modified to catch and hold its prey.
Yes, John, the hind legs of the grasshopper are modified too.
They are modified to jump with.
Ned says he didn't know there was so much to learn about a little thing
like an insect's leg.
Yes, indeed, there is a great deal to learn about all living things.
I wonder how you would like to look at the grasshopper's wings for a
little while.
Here is one with large wings.
[Illustration]
See how they lie along each side of the body.
They come together on top like the ridge of a sloping house roof.
Yes, May, they are the roof to the grasshopper's body, and they help to
protect it.
Let us gently spread them out.
Ah! these roof wings are not what the locust flies with at all.
See, folded up under them is a pair of delicate gauzy wings.
[Illustration]
If we are careful, we can spread them out.
We will use this dead grasshopper that Charlie has found.
What pretty wings! So dainty! And how cleverly they are folded up, like
little fans.
Who would imagine such delicate gauzy wings were folded away under the
hard, stiff roof wings.
The roof wings are called wing covers, because they cover up these
pretty inner wings.
The locust does not fly with the wing covers.
It spreads them out wide to get them out of the way.
It flies with the inner wings.
[Illustration]
How pretty the flying wings are when they are spread out!
See, over there goes a grasshopper whose flying wings are bright yellow.
And there goes another with red flying wings.
Some of the grasshoppers are almost as pretty as butterflies when they
are flying.
They show their gay inner wings only during flight.
As soon as the grasshopper comes to rest the inner wings close of
themselves.
The wing joints act like springs.
The grasshopper does not have to think about shutting up its wings.
[Illustration]
John says it has a spring in its wing covers too.
Open the wing cover.
There, it locks itself, as it were, and stays open without any effort on
the part of the grasshopper.
You see the grasshopper wants its wing covers to stay open and out of
the way of the inner wings when it flies.
So it just opens them, and there they are.
It moves the inner wings very fast indeed when it is flying. It would
not do at all for them to be fastened open.
If it did not move them, it could not fly. The wings fairly _whirr_,
they go so fast. They beat against the air, and thus the grasshopper is
pushed along through the air.
As soon as it is done flying it stops moving the wings, and they
instantly close of themselves.
[Illustration]
Then it unlocks the wing covers and they shut down over the inner wings.
They shut down very tightly. They overlap, as you can see, just below
where they are fastened to the insect's body. Thus they form a very good
roof.
[Illustration]
What wonderful wings the grasshopper has!
And there is something more to be said about them.
Some species of locusts use their wings as musical instruments. When
they wish to, they rub the upper end of the inner wings against the
upper end of the wing covers when they are flying.
This makes the crackling sound we sometimes hear when the locusts fly.
What is that, Mollie? You have caught a locust that has no wings at all?
Who can guess why?
Ah, yes, our wise John says he thinks it is because it is a young one.
What makes you think so, John?