Mosquitoes and Malaria 



195 



Larva: When at rest floats in 

 a horizontal position beneath the 

 surface film. No respiratory 

 tube but instead a flattened 

 area on the eighth abdominal 

 segment into which the two 

 spiracles open (fig. 128). 



Adults: Palpi in both sexes 

 nearly or quite as long as the 

 proboscis. Proboscis projecting 

 forward nearly on line with the 

 axis of the body. When at rest 

 on a vertical wall the body is 

 usually held at an angle with the 

 vertical (fig. 128). Wings fre- 

 quently spotted (fig. 130). 



When at rest (with few excep- 

 tions) floats suspended in an 

 oblique or vertical position, or 

 more rarely nearly horizontal, 

 with the respiratory tube in 

 contact with the surface film 

 (fig. 128). 



Palpi short in the female, in 

 the male usually elongate. Pro- 

 boscis projects forward at an 

 angle with the axis of the body. 

 When at rest on a vertical wall 

 the body is usually held parallel 

 or the tip of the abdomen in- 

 clined towards the wall (fig. 128). 

 Wings usually not spotted. 



These malarial-bearing species are essentially domesticated 



mosquitoes. 



They develop in any accumulation 

 _ _ stands for 



128. (o) Normal position of the lar- 

 vae of Culex and Anopheles in 



pheles, middle; 

 right hand figure. 



pupa, 



of water which 

 a week or more. 

 Ponds, puddles, rain barrels, 

 horse troughs, cess-pools, cans, 

 even the foot-prints of ani- 

 mals in marshy ground may 

 afford them breeding places. 

 It is clear from what has been said regarding the life cycle of the 

 malarial parasite that the mosquito is harmless if not itself diseased. 

 Hence malarial-bearing species may abound in the 

 neighborhood where there is no malaria, the disease 

 being absent simply because the mosquitoes are unin- 

 fected. Such a locality is potentially malarious and 

 needs only the introduction of a malarial patient who is 

 exposed to the mosquitoes. It is found that such patients 

 may harbor the parasites in their blood long after they 

 are apparently well and thus may serve as a menace, 

 just as do the so-called typhoid carriers. In some 

 malarious regions as high as 80-90 per cent of the natives 

 are such malaria-carriers and must be reckoned with in 

 antimalaria measures. 



Based upon our present day knowledge of the life cycle 

 of the malarial parasite the fight against the disease 



128 (b NOTma 

 , n d f 

 n 



