474 THE ANIMALS OF THE EARTH 



and is shed or molted by the maggot. Both of these molts 

 occur in less than a week from the time of hatching. At the end 

 of a week, the inelastic skin turns brown, the creature within it 

 shrinks away from it, and as far as we can see remains inactive 

 for a week. In this stage it is called a pupa. But great changes 

 take place in the maggot during this period, because at the end 

 of the week of quiet an adult fly emerges from the brown skin. 



It requires only two weeks for the 100 eggs laid by a single 

 fly to develop into 100 adult flies. Since most of these flies 

 lay ioo-eggs apiece, the number of flies in the community rapidly 

 increases and becomes a serious menace to health. 



Mosquitoes. The mosquito is an annoying creature, and 

 by its buzzing and biting interferes with our pleasures out of 

 doors and our comforts at home. But its buzzing and stinging 

 are not the worst charges against a mosquito. The strongest 

 reason for dislike of it and warfare against it is that it is a carrier 

 of malaria and yellow fever, and is thus a breeder of disease. 

 Malaria is caused by a germ which lives in the blood of a malarial 

 patient ; when a mosquito bites a person sick with malaria, some 

 of the germs get into the mosquito's body and multiply there. 

 When the mosquito bites another person, some of the malaria 

 germs get into the wound made by its sharp mouth. These 

 germs grow and multiply and spread through the blood of the 

 bitten person and cause malaria. 



Mosquitos, like flies, breed rapidly and the best way to de- 

 crease their number is to destroy their breeding places. About 

 200 eggs grouped together in an irregular mass are laid on the 

 surface of stagnant water by each female. The water in a 

 gutter, in an automobile rut, in an open rain barrel, in the urns 

 of cemeteries, in flower pots, or in discarded tin cans, serves as 

 a breeding place for hundreds of mosquitoes. Larger breeding 

 places are furnished by ponds, pools, and marshes. 



Within a day, the eggs hatch into larvae or small squirming 



