英文科学读本 第三册·Lesson 43 More about Insects

Lesson 43 More about Insects

Shall we see what else we can find to say about insects, Fred? asked Willie. "Norah would be pleased, I am sure."

Very well, said Fred, "suppose we talk about the insect's body. The most important part of the body is the chest. To it are joined the wings above and the legs on the under side."

Most insects have two pairs of wings; some have not a second pair, but have instead a pair of balancers; some have no wings at all. Beetles have two pairs of wings, but the outer ones are simply hard, horny cases, meant to protect the thin, gauzy, true wings beneath.

Insects have always three pairs of legs, which are formed on one general plan—a thigh, a leg, and a foot. Yet teacher says few things are more wonderful than the way in which the legs and feet of each insect are formed to suit the kind of life it has to live.

Some insects, like the grasshopper, have long legs and stout strong thighs for jumping and leaping. Some are meant to burrow in the ground, like the mole and the rabbit. They are provided with short strong fore-legs made for digging.

How wonderful it all is, said Norah.

The bee's legs, continued Fred, "are made hollow at the sides to form a sort of basket, in which it carries home the pollen from the flowers for feeding purposes."

Fred, I think I can remember about the way the insect breathes, said Willie.

Go on then, Will, said Fred.

Teacher says insects have neither lungs nor gills, said Will. "They have instead two long canals in the body, which end in breathing holes, in the loose side skin, joining the upper and lower segments. These canals send out branching tubes into all parts of the body."

The air which is taken in at the breathing holes on the sides of the body is carried into every corner by these tubes, and so the blood all over the body is cleansed. The insect's blood is cold and colorless.

SUMMARY

Most insects have two pairs of wings—some have no wings. All have three pairs of legs. The legs and feet are made to suit the life of each kind of insect. Some are made for leaping, some for digging in the ground. The bee's thighs form baskets. Insects have neither lungs nor gills. They breathe through slits in the loose, side skin.