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THE WESTERN AND NORTHERN LIMIT OF GLOSSINA MORSITANS 



IN NORTHERN KATANGA. 



By Dr. Schwetz. 



(Map I.) 



It is not necessary to insist on the utility of knowing the exact distribution of 

 Glossina morsitans. While its role in the etiology of human trypanosomiasis is not 

 yet fully established, and does not seem to be very important, the same unfortunately 

 cannot be said of animal trypanosomiasis. The obstacle presented by G. morsitans 

 to the breeding of cattle is well known, and the study of the distribution of this 

 fly is therefore of considerable interest and importance from several points of view, 

 entomological, medical and economic. 



In a previous paper on this subject (Bulletin of Entomological Research, December 

 1915) I stated the results of my observations, namely, that this Glossina inhabits 

 only regions where the vegetation is of a particular type, namely, bush or park- 

 like country. On several journeys made in 1913 and 1914 between the River 

 Lualaba and the River Lomami in the region between 9° and 6° S. Lat., I was able 

 to define the spots where the park-like country and G. morsitans disappear almost 

 simultaneously. These spots I described as the western limit of morsitans. I also 

 drew attention to the fact that between 8° and 6° S. Lat. this double limit coincided 

 more or less with the line of the Lualaba-Lomami watershed. But by a scientific 

 scruple I abstained from giving on the map an approximate, theoretical line for this 

 limit and confined myself to indicating the districts actually visited and examined. 

 In the course of 1916 I again made several journeys between the Lualaba and the 

 Lomami, and again determined several points in the western limit of morsitans. 

 I am therefore now able to complete the former map. This time I have also found 

 the northern limit of morsitans. I will explain briefly the result of each of my recent 

 journeys (see Map). 



From Kabonga to Katompe. 



Grassy savannah, here and there more or less wooded, as far as the village Mlenge 

 before the River Lugufu. Then, as far as the village Ngona (River Sangwa Mbusi) 

 transitory vegetation : grassy savannah, scrub, patches of thin park-land (pare 

 degenere), tracts of forest. After the Sangwa Mbusi comes a stretch of typical 

 park, which, however, is not continuous as far as Katompe, being interrupted here 

 and there by more or less long stretches of thin park, wooded savannah and several 

 other kinds of transitory vegetation. 



I would draw attention to two points that can be noticed in studying the map. 

 First, that from the River Luguvu, after the village Mlenge, the basin of the Lomami 

 is left, the streams and rivers that follow being intermediary tributaries of the 

 Lualaba. Second, that the Kabongo-Katompe route is parallel to that from Kabongo 

 to Kisengwa ; but while the latter follows the basin of the Lomami, the former 

 leaves it after the River Luguvu. But the park commences at exactly 15 km. after 



