The Insect Folk Part 15

Now, let us look at the other legs.

The front pair are the smallest.

Can you find the little c.o.xa 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 gra.s.shopper's body.

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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 gra.s.shopper'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.

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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 c.o.xa 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 gra.s.shopper 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 gra.s.shopper's wings for a little while.

Here is one with large wings.

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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 gra.s.shopper'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.

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