The relative numbers of different species. 



species have of secreting themselves among the straw of a thatched 

 roof and of resting only upon objects which are as nearly as 

 possible the same colour as they are themselves, are very important. 

 In order to exemplify this, it seems worth while to recount an 

 instance which happened in our experience. In the malarious 

 village of Ennur in the Madras Presidency, A. rossi was so 

 abundant that on almost every straw of the thatched roof of every 

 house three or four specimens of this species were resting. A 

 careful search in the ordinary way did not reveal the presence of 

 any other species, and it is certain that, had there been no other 

 object in the search than the mere determination of the species of 

 " anopheles " present in the village, the observer would have gone 

 away quite satisfied that A. rossi was alone present. But the 

 village was an extremely malarious one, and knowing that 

 A. rossi was an inefficient carrier of malaria in nature, he was un- 

 willing to believe that no other species was present in the houses. 

 Fixing his mind, therefore, upon the thought that he was looking 

 for A. culicifacies and not for A. rossi, he again commenced the 

 search with great care, and was rewarded not only by detecting the 

 presence of A. culicifacies, but by catching a sufficient number of 

 this species during several days' work, to prove that it was the 

 species responsible for the prevalence of malaria in the place and 

 not the very much more abundant species A. rossi. 



THE FOOD OF ANOPHELES. THEIR NOCTURNAL HABITS. 



Mr. Theobald reports that one species of "anopheles," viz., A. 

 maculipennis, does not habitually feed on blood in England. Nuttall 

 and Shipley, however, found that this species readily sucked blood in 

 laboratory experiments. All the species known to us in India certain- 

 ly feed chiefly, if not entirely, on the blood of men or of animals. 

 In laboratory experiments seven species, with which experiments 

 were made, readily sucked blood every night for several weeks, in 

 spite of the fact that they had not completely digested their previous 

 meals. Fuliginosus, culicifacies, listoni, and rossi also fed readily 

 on the blood of pigeons and sparrows. 



Anopheles feed almost exclusively at night or in the early 

 morning just before dawn. During the daytime, even if they are 

 taken into a dark room, it is almost impossible to get them to 

 suck blood. Exceptional instances have been recorded and have 



54] 



