1.What becomes of the flies in winter？There is not one of all thesummer swarmto be seen.Theydo not hide in corners，and go to sleep all winter，as some animals do.All，except a very few of them，die when the cold weather comes.Then where do all the flies come from in summer？
2.Before the flies die，they lay their eggs in some out-of-the-way place，where they remain hidden during the winter months.These eggs are hatched by the sun’sheat when the warm weather comes.The little creature that comes out of the egg is not a fly，and it does not look as if it ever would become one.It is a little white worm-a maggot.
3.This little worm is sure to find plenty of food near，for the mother fly knew by instinctwhat kind of foodwould suit the little one whom she would never live tosee，and she laid the egg in a place where plenty of this food was to be found.
4.It begins at once to cat，and it does eat with a right good will.The first day of its life it eats twice its own weight of food，and as it grows its appetitebecomes keenerstill.With such an appetite it is notstrange that the creature grows rapidly.After a time it stops feeding，and begins to make a little case for itself，in which it shuts itself up for a long sleep.If you were to see it at this stage，you might think it had no life.It does not see，it does not move.
5.By-and-by，however，it wakes up，forces its way out of the case in which it has been sleeping，and comes out a complete fly，with eyes，feelers，wings，and legs just like those of its mother.
6.All the gay butterflies and moths，and other insects which you see flying about，began life in the same way-as a worm or caterpillar，which was hatched from an egg.They all go to sleep for a time in a hard case which they make for themselves，before they change into the full-grown winged creatures which we know so well.
7.We usually think of flies as both useless and troublesome creatures，but they have a very importantwork to do for us.They are an army of little scavengers ，always on the watch to pounceupon little particles ofdecaying matter，which，but for them，would poison the air and form a danger to our health.
8.As these little pieces of waste matter are generally very small-often mere dust-flies must be very keen-sighted in order to find them；and so they are，for their eyes are so large as almost to cover both sides of their heads.
9.When you see it through a microscope，the eye of a fly looks like a great number of very small windows placed close beside each other.Now，each of these little windows or spaces is really a complete eye，and there are about four thousand of them in each big eye.No wonder，then，that not a speck of waste matter escapes their sharp sight.
10.The foot of a fly is no less wonderful than its eye.Have you ever wondered how it could walk on the smooth window-pane or even onthe ceiling overhead without slipping or falling？Whenyou learn more about its foot，you will be surprisedat its power of letting go rather than at its power of holding on.
11.Each foot has two sharp hooked claws for climbingup a rough surface；but in order to prevent slipping ona smooth surface，the sole of the foot is kept wet with a strong glue or cement which it makes for itself.
12.Sometimes the fly stays too long in one spot，and the cement hardens，so that he cannot lift his foot.He has then to break off his leg before he can get clear，and it even happens sometimes that he is held a prisoner in this way until he starves to death.