1.The common fly which you so often see on the window-panes is called the house-fly.The large flies which are so fond of meat are called blow-flies.
2.They are not the same as the housefly.A fly never grows bigger after it has become a fly，so that small flies and large flies cannot be of the same kind.
3.Do you know why the fly is called an insect？It isbecause its body is made up of three parts，which are nearly cut apart from one another-the head，the chest，and the belly.The word insect means cut into，and the fly’s body looks as if it had been nearly cut into three pieces.
4.Flies have no bones inside their body；but they have a hard skin like a shell all over the outside，and their flesh is inside this hard skin.
5.Look at the head of the fly.Do you see its two large eyes，with which it can see on every side？Then it has two feelers，which stick out in front like little brushes.
6.The mouth of the fly is a little trunk or tube，like the trunk of a very tiny elephant.Watch a fly when it rests on a lump of sugar，and you will see it putting out its trunk and sucking up the sweet juice.
7.The fly has two thin clear wings，one on each side.It has also six legs.Its wings and its legs are all joined to its chest.
8.The foot of the fly has two small claws for holding on with.It has also two pads，which are always covered with a sticky gum；and this keeps its foot from slipping on any smooth place.By this means also the fly can walk on the ceiling without falling.
9.Flies feed on dirt of all kinds.They are ofsome use in eating up what would cause a badFOOT OF FLY（苍蝇的足）smell.They are also very fond of sweet things，like treacle and sugar.
10.The fly lays its eggs on pieces of meat，or something else that will serve as food for its young.These eggs look like tiny white balls.But it is not a small fly that comes out of the egg.It is a little white worm.
11.These worms eat a great deal，and then they go to sleep.They become hard and dry，as if they were dead.But soon this dry case bursts open，and out comes a full-grown fly.Is not this a strange way for a fly to be born？
12.Bees and butterflies and other insects pass through the same changes before they get their wings.
SUMMARY
The fly is an insect.It has no bones.Its flesh is covered with a hard skin or shell.It has two large eyes and two feelers.Its mouth is like a little trunk or tube.It has two wings and six jointed legs.Its feet are so made that it can stick on to any place.The fly lays its eggs on something that will give food for its young.Out of the egg a little white worm appears.After it has eaten a great deal，the worm goes to sleep for a long time.Then it bursts its case，and becomes a full-grown fly.
【中文阅读】
1．小朋友，你在窗玻璃上经常看见的普通苍蝇，叫“家蝇”，英语是house-fly。那种特别喜欢吃肉的大苍蝇，叫“丽蝇”（blow-fly）。①2．丽蝇和家蝇是不一样的。苍蝇在变成苍蝇之后，就再也不长个儿了，所以小苍蝇和大苍蝇不可能是同一种。
3．你知道苍蝇为什么叫“昆虫”吗？因为苍蝇的身体是三部分组成的，三个部分之间，看起来就像要被切开一样：头部、胸部、腹部。昆虫的英语叫insect，意思就是“切进去”。苍蝇的身体看上去也好像是“切”成三部分的。②4．苍蝇的身体里没有骨头，但是外面有一层甲壳一样的硬皮，硬皮的里面是肉。③5．看看苍蝇的头。你看见它的两只大眼睛了吗？这两只大眼睛可以看到每一个方向。头上还有两根触角，像两把刷子一样，突出在脑袋前面。
6．苍蝇的嘴是一个“小象鼻”或“管子”，就跟一头非常小的象的鼻子一样。观察一下，苍蝇落在一团湿润的糖上，就能看见它伸出嘴来吸食糖水。④7．苍蝇有两只透明的薄翅膀，一边一只。苍蝇还有六条腿，翅膀和腿都是从胸部长出来的。⑤8．苍蝇的脚上长着两个小爪子，用来抓住东西。还有两个爪垫盘，一直覆盖着一层粘液，这样苍蝇在光滑的表面上，脚就不会打滑，而且还可以在天花板上爬行，不会掉下来。
9．苍蝇什么碎屑都吃。可以用苍蝇来吃掉一些会产生臭味的东西。苍蝇还喜欢甜的东西，比如糖浆、砂糖。⑥10．苍蝇把卵产在肉上，或者其他能当幼虫食物的东西上。苍蝇卵看起来像白色的小球，但里面出来的不是小苍蝇，而是一种白色的小虫子，学名叫“蛆”。
11．这些小虫子要吃很多东西，然后就睡着了，身体变得又干又硬，好像死了一样，学名叫“化蛹”。但是很快，这层干燥的硬壳就会破开，爬出来苍蝇的“成虫”。苍蝇这样的出生过程，不是很奇怪么？⑦12．蜜蜂、蝴蝶和其他的昆虫，在长出翅膀以前，也要经历一样的变化。
译注
①苍蝇属于“节肢动物门”“昆虫纲”“双翅目”“环裂亚目”。家蝇和丽蝇分属不同的科。
②汉语里的“昆”代表“众多、庞大”的意思。“昆虫”在生物学的分类中，属于“动物界”的“节肢动物门”的“昆虫纲”，这是动物界中最大的一门中的最大的一纲，已经发现了100多万种，所以叫“昆”也就名副其实了。昆虫纲的最大特征是胸部有三对足。
③硬皮的学名是“外骨骼”。
④这种嘴，学名叫“舐吸式口器”，那个“象鼻”一样的东西，学名叫“喙”，但和鸟嘴的“喙”完全不一样。这里的“糖块、糖团”（lump）从上下文看是有水分的，所以我加上了“湿润”二字。
⑤其实苍蝇还有第二对翅膀，但是已经退化成了“平衡棒”。
⑥“用苍蝇吃东西”可能指的是一种有点吓人的治疗方法：蛆可以吃掉人身上坏死的组织，救人一命！这种疗法叫“蛆虫清创技术”（maggot debridement therapy）简称MDT。早在几百年前，拿破仑军队和美国南北战争的军医就用过这种疗法。2006年4月，中国大连的一家医院也在国内第一次成功采用了蛆虫疗法。此外，苍蝇的幼虫还是极好的饲料，有重要的经济价值；苍蝇自身的免疫能力也是科学家研究的对象。
⑦这个“卵-幼虫-蛹-成虫”的过程，学名叫“完全变态”。这句话是一个生物学术语，可不是平时开玩笑的时候说的意思！还有一些昆虫，比如蝗虫，那四个步骤不完全，只有“卵-若虫-成虫”三个阶段，没有明显的幼虫期和蛹期，也就是“不完全变态”。
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