244 TROPICAL MEDICINE AND HYGIENE 



short in both sexes. Scutellum trilobed. In some 

 genera hairs on scutellum and metanotum. 



Malaria. The known carriers of malaria all belong 

 to the division of the mosquitoes known as Anophelince. 

 All anophelines do not serve equally well as carriers of 

 malaria. Some species are readily infected, others only 

 with difficulty, and some not at all. The dangerous 

 species are those which are numerous and readily convey 

 the disease. 



For economic and efficient prophylaxis a knowledge 

 of the habits of each species is required, and it is found 

 that the different species vary greatly in their habits, life- 

 history, and breeding-places. 



In any place or country the species of anophelines 

 must be determined ; those that are good carriers of 

 malaria must be found out experimentally or must be 

 found infected and the breeding places and habits of 

 these must be studied in great detail. 



The anophelines, which include all the known carriers 

 of human malaria, are easily distinguished from other 

 mosquitoes, which have a straight, penetrating proboscis. 



(1) The palps in both male and female are practically 

 the same length as the proboscis, and in the male are 

 clubbed. 



(2) The scutellum, which is more or less trilobed in 

 other mosquitoes, shows no sign of such lobing in the 

 anophelines. 



(3) The scales on the veins of the wings are lanceolate 

 in the anophelines, whilst they vary greatly in the other 

 Culicidce. 



(4) The proboscis is nearly in the long axis of the 

 head, thorax and abdomen, so that the mosquito almost 

 forms a straight line. When at rest, as the proboscis 

 points towards the surface on which the mosquito rests 

 the abdomen points away from it. 



(5) The larvae have no respiratory siphon ; they lie 

 flat on the surface of the water and after their first moult 

 have curious palmate tufts on the latero-dorsal surface 

 of the abdomen on each side. 



