484 MAN CONTROLS HIS ENVIRONMENT FOR HEALTH 



who has malaria. The only cure for the disease is frequent doses 

 of quinine. This kills the parasites in the blood. 



Workbook Exercise. Using the text and diagram, work out a life 

 cycle of the malarial parasite. 



Demonstration 4. To show life history of a mosquito. 



Use charts or material in Riker mounts, to show history of any mosquito. 



The malarial mosquito. Fortunately for mankind, not all 

 mosquitoes harbor the parasite which causes malaria. The harm- 

 less mosquito {Culex) may be usually distinguished from the mos- 

 quito which carries malaria (Anopheles) by the position of the body 

 and legs when at rest. Culex lays eggs in tiny rafts of one hundred 



acCult cccCult 



How does the common mosquito, Culex (on left), differ in the various stages of growth from the 

 malarial mosquito, Anopheles (on right) ? 



or more in standing water ; thus the eggs are distinguished from 

 those of Anopheles, which are not in rafts. Rain barrels, gutters, 

 and old cans may breed in a short time enough mosquitoes to 

 annoy a whole neighborhood. The larvae are known as wigglers. 

 They appear to hang on the surface of the water, head down, in 

 order to breathe through a tube at the posterior end of the body. 

 In this stage they may be recognized by their peculiar movement 

 when on their way to the surface to breathe. The pupa, dis- 

 tinguished by a large head and thoracic region, breathes through 

 a pair of tubes' on the thorax. 



