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work its deadly way. It was pointed out that one of the first 

 problems to be solved in this connection is the destruction 

 of all blood-sucking insects an enormous task, but one that 

 is being slowly and surely accomplished. In the case of malaria, 

 the successful methods adopted were due to the following line of 

 reasoning : Anopheline mosquitoes have been proved to carry 

 malaria. This insect feeds at night. As a first precaution, 

 sleeping-rooms should be made mosquito -proof by having all 

 openings covered with a fine gauze. Further, we know that 

 these insects lay eggs in expanses of water, where, when hatched, 

 they pass through larval and pupal stages, and finally emerge as 

 fidults. Consequently, to reduce the number of mosquitoes, an 

 attack may be made on the immature stages. By systematic 

 drainage the extent of the breeding-grounds may be reduced. 

 When this is impossible, knowing that the larvae come to the 

 surface to breathe, we can put a film of kerosene or other oil on 

 the surface of the water, and kill off the larvae by blocking the 

 breathing-tubes, and so on. In the case of yellow fever, carried 

 by Stegomyia, it was found that the eggs are not laid in large 

 expanses of water, as in the case of anophelines ; but this insect 

 prefers small collections, such as those contained in tin cans, 

 broken bottles, or small earthenware pots. Consequently, a 

 crusade was started to abolish all such receptacles. By this 

 means, Stegomyia fasciata, with its attendant disease, yellow 

 fever, has been practically banished from many places where 

 previously it had a strong hold. Sleeping sickness is not such 

 an easy problem, as we are not yet in possession of sufiicient 

 information as to the habits and life-history of the tsetse to 

 attack this insect in the way which may eventually be possible. 

 We know, however, that it is pseudo-viviparous. The female 

 deposits an immature pupa, which burrows into the ground, and 

 from which, after a time, the adult emerges. We also know that 

 the mature insect must live in shade, near water. In Uganda 

 this fact has been made use of in combating the disease. Villages 

 near lakes where tsetse and sleeping sickness were abundant were 

 removed to open, well-cleared ground, which the fly would not 

 invade, and the result has proved an enormous success ; in fact, 

 it has probably saved the population of Uganda from absolute 

 annihilation. Another method recently adopted with some 

 measure of success has been the introduction into breeding- 



