156 



species " plentiful, and a painful biter in the early mornings after 

 sunrise." 



On this subject the reader is referred to what 



Stomoxys nigra nas been written above, under the headings 



as a " Stomoxys calcitrans as a disease-carrier. . . . 



Disease-Carrier. Q^^ Trypanosomiases (in Africa)," especially 



the concluding remarks on p. 153. It will be 

 seen that, in experiments on the transmission of trypanosomes by 

 Stomoxys in Uganda and other parts of Africa, S. nigra as well as 

 S. calcitrans was used, so that the results must be taken as applicable 

 to both species. As already stated, it has been shown by experiment 

 that Stomoxys nigra, Macq., like S. calcitrans, L., " can convey 

 trypanosomes directly from an infected to a healthy animal, when 

 the bites follow one another immediately." Apart from the 

 experimental evidence, such as it is, one or two observations with 

 reference to S. nigra as a disease-carrier may be mentioned 

 for what they are worth. Thus, a tube of specimens of this species 

 in the Museum Collection, collected at Ngatana, East Africa 

 Protectorate, by Dr. J. W. Gregory in 1893, bears the label 

 in Dr. Gregory's handwriting : " Blood-Sucking Flies (Killed 

 our Camels)." In a letter written on November llth, 1903, when 

 forwarding the examples of S. nigra collected by Captain Nickerson 

 at Dem Zobeir, in the Bahr-El-Ghazal Province of the Anglo- 

 Egyptian Sudan, the late Major Lewis (who at that time had 

 recently returned from the Sudan) stated that the flies were 

 " responsible (either directly, or as vehicles of some organism) for 

 a form of virulent disease among donkeys, mules, horses, and 

 camels." It may be observed that, since Olossina morsitans, 

 Westw., occurs at and in the vicinity of Dem Zobeir, the idea 

 naturally suggests itself that the disease may have been nagana, 

 and that if Stomoxys nigra was indeed concerned in its dissemination, 

 the flies may have conveyed the trypanosome directly from animal 

 to animal, as suggested by Montgomery and Kinghorn in the case 

 of cattle-trypanosomiasis in North- Western Rhodesia.* In a 

 subsequent letter, however, Major Lewis wrote : ' There is not 



* Vide supra, p; 152. 



