164 



20. Have you any reason to suppose that tsetses may be capable of 

 subsisting on the juices of plants or that they suck up water or dew ? 



21. Do you personally know any facts tending to show that tsetses 

 move about with big game either in the natural migrations of the latter 

 or when they are driven away, and return when or soon after the game 

 returns ? 



22. Are you acquainted with any instance in which the appearance of 

 tsetses in a new locality has been due to the movement of natives ? 



23. Do you know personally of any cases of healthy domesticated 

 animals of any kind living at a Kafir kraal within a fly-belt ? " 



To the foregoing, the following supplementary questions may be 

 added : 



24. Have you found Tsetse-fly breeding places in the fly-belt studied ? 

 What is the nature of the soil and vegetation in the places where you 

 have found pupae ? What is the position of these spots in relation to 

 water, shelter, etc., and what is their orientation ? 



25. In the fly-belt, what is the ratio of the sexes at different seasons 

 of the year ? Is this ratio a real one, or is it due to the fact that the 

 females are less easy to catch or that they remain concealed ? 



26. Have you ever observed a special migratory movement of females, 

 tending to pass from localities favourable to reproduction to others less 

 favourable ? 



27. Have you observed that external agencies cold, heat, humidity, 

 solar radiation have any influence whatever upon the activity and 

 length of life of Tsetse-flies of either sex ? 



28. Have you observed the presence of parasites in Tsetse pupae ? 

 In the pupae collected by you, what proportion was parasitised ? To 

 what species did the parasite belong ? 



FURTHER SUGGESTIONS FOR FUTURE WORK. This little volume may 

 fittingly conclude with a brief reference to the " Report of the Glossina 

 Sub-Committee of the Imperial Bureau of Entomology " (171), 

 published about two years ago. 



Attention is drawn in this report to the necessity for further know- 

 ledge of the life-histories of the various species of Tsetse-flies, as well as 

 of their habits and the factors that favour their increase or inhibit their 

 spread, before the wide areas over which they range can be reduced. 

 The measures hitherto recommended for the eradication of Glossina 

 cannot be carried out effectively over large stretches of country, and 

 will only prove useful in restricted portions of such areas if persistently 

 maintained over a considerable time. 



An essential line of investigation will be a thorough survey in each 

 infested locality. The surveys will require checking at intervals 

 throughout the year, and should include estimates, on a standard basis, 

 of the density of the fly. The points suggested for observation and 

 experiments are distribution of the flies ; effects of clearing ; breeding 

 grounds ; food of the flies ; their parasites and other enemies ; 

 destruction of adults ; and influence of odours. Zululand, Southern 

 Rhodesia, Nyasaland, Tanganyika Territory, the Sudan and Northern 

 Nigeria are suggested as the most suitable countries for the establish- 

 ment of experimental stations to investigate these problems. The 

 precise areas selected in these countries should represent different types 

 of environment, and should, so far as possible, be situated in localities 

 in which the presence of Tsetse-flies is actually obstructing settlement, 

 or is likely to do so in the near future. Suggestions are made for 

 the organisation of the staff for these stations, which, as the work 

 progresses, will necessarily include a protozoologist. 



