CLASSIFICATION 437 



they have laid their eggs but some species may live for four months 

 or more. The species which lay all their eggs in a mass at one 

 time are short lived, and have several generations a year, whereas 

 those in which the eggs are laid in small lots, at intervals, live for 

 several months. Species in which the females hibernate are still 

 longer lived, but since they are not active in winter their effec- 

 tive life is short. 



Classification. Over 500 species of mosquitoes have been 

 described, the majority of which belong in the tropics, although 

 the north is richer in individuals. The task of classifying all of 

 these species into subfamilies and genera is one which has taxed 

 the wits of many scientists. The wide discrepancies in the work 

 of different men as regards mosquito classification is the best 

 possible proof of the difficulties in the way. As in many other 

 groups of -animals, intensive study has tended to magnify the 

 value of certain characteristics as criteria of genera or subfamilies, 

 the result being the breaking up of what would ordinarily be 

 looked upon as a single group into a number of poorly denned 

 and intergrading groups. Theobald, who has written a mono- 

 graph of the mosquitoes of the world, separates the Corethrinse 

 (forms without a long proboscis) from the mosquitoes, and 

 divides the remainder of the family into ten subfamilies and a 

 very large number of genera based largely on scale character- 

 istics. On the other hand, Howard, Dyar and Knab, whose classi- 

 fication is adopted here, recognize only two subfamilies the Core- 

 thrinae and the Culicinse, the latter including all the true mos- 

 quitoes. The Culicinse are further divided into two tribes, the 

 Sabethini, including chiefly forest-dwelling non-blood-sucking 

 forms, and the Culicini. The genera of the latter are arranged 

 in a series from the primitive forms of the genus Anopheles to 

 such highly specialized forms as Megarhinus. 



The identification of species of mosquitoes, or even of genera, 

 is often very difficult for anyone but a specialist. Fortunately 

 some of the most important disease-carrying species are so 

 marked that they can quite readily be distinguished even by 

 a novice. Only a few of the disease-bearing species can be 

 separately described here. 



