CULICID.F, OR MOSQUITOES 555 



(fig. 393), which moves in jerky movements, remains in the water, but partakes of 

 no food. In shape it somewhat resembles a tadpole, that is to say, it consists of a 

 bulky anterior portion, on the surface of which the head, with its appendages, is 

 recognizable, and a more slender segmented abdomen. Above, on the thorax, there 

 are two small trumpet-shaped breathing tubes for the conveyance of air to the 

 tracheal system. After three or four days the perfect mosquito hatches out, remains 

 a short time on the surface of the water until its chitinous integument is hardened, 

 and then flies away. 



The females that are fertilized in the autumn hibernate in sheltered spots in the 

 open air, or in houses, cellars, under stairs, in stables, barns, etc., and are the 

 progenitors of the first generation of the following year. 



In accordance with the climate of a country, or the kind of weather of a year, 

 the conditions in regard to the manner of life and the duration of the development 

 of the mosquito vary. At all events, the life-history of the mosquito elucidates 

 many points relating to malaria which were hitherto not understood. 



[The length of the egg, larval and pupal life varies so much that it is not 

 possible to give an account of any value here. Frequently the eggs may incubate 

 in two days, whilst I have had Stegomyia fasciata eggs from Cuba that have hatched 

 out under abnormal circumstances more than two months after they were laid 

 (" Mono. Culicid.," iii, p. 6). Some larvae, as Anopheles bifurcatus, live for 

 months during the winter. Some mosquitoes therefore hibernate as larvae. The 

 larvas and pupae of the different genera present very marked characters, mainly in 

 regard to the structure of the siphons. Specific differences may be found in the 

 frontal hairs of Anopheline larvae and in the number and arrangement of a group 

 of spines at the base of the siphon in Culicines. F. V. T.] 



Culicidse or Mosquitoes. 



The importance of these insects to man is very great. They not only produce 

 painful bites, which may become inflamed and give rise to a considerable amount 

 of cedema, but they are more important on account of the part they play in the 

 distribution of various diseases. Culicidce may not only carry disease germs, but 

 act as intermediate hosts for certain parasites, such as some of the Anophelina for 

 malarial parasites, Culex for Filariae, and Stegomyia for yellow fever, etc. ; the last- 

 named is in any case the distributor of that fatal disease. It is therefore very 

 necessary to know the life-history, habits and characters of these pests. 



Mosquitoes exist in almost all parts of the world from the Arctic circle to the 

 tropics ; temperate regions suffer from them less than the two extremes, but even 

 there they form not only a source of great annoyance but of danger as malaria and 

 possibly now and again yellow fever carriers. A few years ago comparatively few 

 species were known, now some 800 odd have been described. Their number will 

 probably not stop far short of 1,000, in spite of the fact that many have been 

 described under different names, yet really the same species, Some are purely 

 domestic, others entirely sylvan ; the former, as we might expect, often have a very 

 wide distribution, having been taken from place to place in boats and trains. The 

 more rapid transport becomes, the greater becomes the possibility of this wide 

 distribution of many species increasing, and the spread of other species from their 

 natural home to foreign parts by sea and then by trains further inland. 



All CulicidcE are aquatic in their larval and pupal stages. Almost all small 

 collections of water, both natural and artificial, may form breeding grounds for 

 these pests. Some even breed in pitcher plants and many in bromelias. The 



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