MONOGRAPH 



OF TH'E 



ANOPHELES MOSQUITOES 



OP INDIA. 



CHAPTER I 



A GENERAL ACCOUNT OF MOSQUITOES 



I 



jEFORE commencing the study of any particular 

 kind of mosquito it is necessary to know something 

 of the general characters, life history, and structure 

 of this important family of insects. 



Mosquitoes or gnats (Culicidce) belong to the 

 order of insects known as Diptera. As is well-known, a typical 

 member of the class Insecta has four wings, but it is characteristic 

 of members of the order Diptera that the hinder pair of wings are 

 so reduced in size as to form only small knobs called " balancers " 

 or halter es, so that Diptera are often spoken of as " two- winged 

 flies." Other important characteristics of members of this order 

 are that they possess piercing and sucking mouth parts, and that 

 they undergo complete " metamorphosis " a term which is ex- 

 plained by Glaus in the following manner : 



" The more complete the agreement between the just-born young and the adult sexual animal 

 so much the greater will be the duration of the embryonic development and the more complicated 

 the developmental processes of the embryo. The post-embryonic development will, in this case, 

 be confined to simple processes of growth. When, however, the embryo is born in an immature 

 condition and at a relatively low state of organization, the post-embryonic development will be 

 more complicated, and the young animal, in addition to its increase in size, will present various 

 processes of transformation and change of form. In such cases the just-hatched young, as opposed 

 to the adult animal, is called a Larva and develops gradually to the form of the adult sexual 

 animal. The development of larvas, however, is by no means direct and uniform, but is compli- 

 cated by the necessity for special contrivances to enable them to procure food and to protect 

 themselves ; sometimes taking place in an entirely different medium, under different conditions of 

 life. This kind of post-embryonic development is known as metamorphosis." 



The phenomena of metamorphosis are exceedingly well shown 

 in the life history of frogs and in that of most insects. The differ- 

 ent stages through which mosquitoes pass before they reach the 



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