ENTOMOLOGY 267 



establishing these organizations, which should be financed and con- 

 trolled internationally, are obviously very great, but failing this, 

 African agriculture will continue to pay heavy periodical tribute 

 to locusts. The matter is urgent, since definite signs of the approach 

 of a new swarming period of the desert locust have been observed 

 on the Red Sea coast of the Sudan during the winters of 1936-7 

 and 1937-8 and local measures to suppress the incipient outbreak 

 may prove to be insufficient. 



TSETSE FLIES 



The part of Africa inhabited by tsetse flies includes most of the 

 tropics, and is a belt of country nearly 2,000 miles wide. The nor- 

 thern boundary runs very roughly from the mouth of the Senegal 

 River through Lake Chad and Lake Rudolf to the coast of Italian 

 Somaliland, and in the south the boundary bisects Angola, runs 

 southward along the boundary between that territory and Northern 

 Rhodesia, and then bisects Southern Rhodesia and Mozambique, 

 west to east. The bulk of the land between the boundaries is in- 

 fested by one or more of the twenty-one species of Glossina, and 

 consequently by trypanosomiasis of domestic animals and of man, 

 diseases which are transferred from host to host by the fly. 



In the British territories, trypanosomiasis of cattle, often called 

 Nagana fever in Eastern Africa, aflfects a very wide area, particu- 

 larly in Tanganyika of which two-thirds is under fly, the Rhodesias, 

 Nigeria, and the Gold Coast. In these territories the treatment of 

 the disease and possibilities of fly control occupy much of the atten- 

 tion of veterinary departments, and of the special Tsetse Depart- 

 ment in Tanganyika. Study of this problem has served to show its 

 great complexity. 



Human trypanosomiasis (sleeping sickness) is due either to 

 Trypanosoma gambiense or Trypanosoma rhodesiense^ and the tw^o forms 

 of the disease are now known to involve rather different problems. 

 Gambiense transmission has been shown to be from man to man, 

 through the agency of tsetse fly; rhodesiense is probably disseminated 

 in the same way, but it is also thought to be capable of transmission 

 by wild animals which carry it in a dormant state. Hence in the 

 control of the latter type of sleeping sickness, which is prevalent 



