60 



" The three large species, G. brevipalpis, G. longipennis and G. 

 jusca, may also be separated from the others by their being mainly 

 crepuscular or nocturnal in their habits, instead of being most active 

 in sunshine." 



CHAPTER VI. 



DISTRIBUTION OF TSETSE-FLIES IN BELGIAN CONGO. 



Since Belgian Congo has been comparatively little visited by British 

 entomologists, we think it may prove useful to devote a few pages 

 to the distribution of Tsetse-flies in that country. For a considerable 

 portion of the statements printed below we are indebted to the remark- 

 able report on the Travaux de la Mission Scientifique du Katanga, by 

 Drs. J. Rodhain, C. Pons, F. Van den Branden and J. Bequaert 

 (116-118), published at Brussels, in 1912, though we have added certain 

 data derived from other publications. 



DISTRIBUTION OF G. palpalis. As is well known, G. palpalis abounds, 

 throughout the entire Congo basin, with the exception of Upper 

 Katanga. 



Lower Congo. According to Dr. J. Bequaert, G. palpalis is the only 

 representative of its genus found in Lower Congo, where it haunts the 

 numerous narrow strips of forest which traverse the savannah, fringing 

 the watercourses and decking even the smaller valleys. In these 

 belts of leafy and luxuriant vegetation, the fly finds a humid atmosphere 

 and kindly shade, and, thanks to these biological conditions, it pene- 

 trates into the interior to a considerable distance from the banks of 

 the Congo. At Kisantu on the Inkisi, 37J miles from its mouth, 

 Dr. Bequaert met with G. palpalis in abundance, and he thinks that 

 it would be interesting to determine the distribution of the insect 

 along the various rivers with which the Lower Congo region is seamed, 

 taking into account the influence of the seasons. If this were done,, 

 we might perhaps succeed in discovering some biological peculiarity 

 in the distribution of the fly, which could serve as a starting-point 

 in an effective campaign against it. 



Central Congo. Dr. Bequaert has recorded observations made by 

 him upon G. palpalis, in the course of a journey from Leopoldville to* 

 Stanleyville. The greater part of the route traverses the equatorial 

 forest, in which the hot and humid atmosphere, coupled with the 

 dense shade on the banks of the river, constitute the ideal biological 

 conditions required by this species of Glossina. The result is that 

 the fly is extremely abundant everywhere, and not a day passes on 

 which it does not come on board the steamers in numbers. 



At Ponthierville and in its immediate environs, however, Dr. 

 Bequaert was surprised to find that G. palpalis apparently did not 

 exist. It may therefore happen, even in the midst of the equatorial 

 region, that there are places from which G. palpalis is absent, although 

 they seem to include all the biological conditions necessary for the life 

 of the adult fly. This is doubtless due to the nature of the soil, which, 

 around Ponthierville, consists of red clay, and is therefore incompatible 

 with the existence of breeding places, since the latter appear always 

 to be established in spots which are sandy, dry, and sufficiently shaded. 



Above Ponthierville, as far as Kindu, G. palpalis is much more 

 rare ; the biological conditions on this portion of the banks of the 

 Lualaba are apparently less favourable than those on the banks 

 beginning at Bangala. 



