WANDOEOBO- OR DONDEROBO-FLY. 305 



would naturally suck up some of the hajmatozoa with the blood, 

 and that the presence of living parasites in the stomach of the 

 fly by no means proves that the latter is capable of communi- 

 cating the disease. On the other hand, if the parasites remain 

 alive in the alimentary canal of Stomoxys sufficiently long, it is 

 possible that some of them might make their way back into the 

 proboscis, as Colonel Bruce supposes them to do in the case of 

 the Tsetse, and so be subsequently introduced into the blood of 

 another animal. Or one might suppose Stomoxys to be capable 

 of conveying the parasites directly from an infected to a healthy 

 animal, by flying to and biting the latter immediately after 

 sucking blood from the former, just as Rogers [XIX.] in India 

 found that the Trypanosome of Surra could be conveyed by horse- 

 flies. In view of Rogers' results, it is certainly curious that no 

 instance of a spontaneous outbreak of Nagana, due to the direct 

 transference of the parasite from diseased to healthy animals by 

 flies other than Tsetse, occurred in the course of Colonel Bruce's 

 experiments on the Ubombo Mountain in Zululand.* This, of 

 course, does not prove that such cases may not sometimes occur 

 under natural conditions, when in the same locality blood-sucking 

 flies other than Tsetse and the parasites of the disease in the 

 blood of wild animals are both numerous. 



Turning to the hoi'se-flies (Tahanidae), we find a certain 

 amount of evidence from East Africa tending to show that if 

 present in sufficient numbers their bites may be fatal to domestic 

 animals. The so-called " Wandorobo "- " Donderobo "- or " Ndo- 

 robo "-flyf of the Wadschagga and Masai is as yet unidentified, 



* Cf. Appendix A, pp. 273-274. Colonel Brace's expei-ience is in 

 accordance with Kirk's statement [28] that "no danger" has been found 

 to result from cattle bitten by Tsetse " mixing with others." 



t Cf. Oscar Baumann, "Duroh Massailaud Zur Nilquelle " (Berlin: 

 Dietrich Reimer, 1894), p. 28 — [Translation] "The loss in personnel in 

 Umbugwe made itself felt, besides which our baggage-donkeys had 

 suffered from the sting (Stich) of the Ndorobo-fly. This insect frequents 

 water-courses and is dangerous to donkeys, since it stings them in the 

 anus, which results in swellings and death." (This refers to the region 

 near Lake Manyara, W.S.W. of Kilima-Njaro.) Cf. also Otto Kersten, 

 "Baron Carl Claus von der Decken's Reisen in Ost-Afrika in den Jahren 

 1859 bis 1861 " (Leipzig und Heidelberg : C. F. Winter'sche Verlagshand- 

 lung), Band I. (1869), p. 249, Band II. (1871), p. 36. The region referred to 

 in the following passage (Bd. I., p. 249) is the Wateita Country, inland 

 from Mombasa. [Translation] " We had rescued the donkeys from the 

 robbers' hands, but only to see them die after all the same day : in the 

 case of three of them, blood and matter escaped from the nose, the head 

 and genital organs were swollen, and the air-passages were so narrowed by 

 ulcers that their breathing resembled a rattling — they were stung by 

 Donderobo flies ! I myself have never caught sight of the poisonous fly, 

 and have not been able to get possession of any in spite of the offer of a 

 reward ; but the natives declared that it was only the sting of the 

 Donderobo, which was frequently dangerous to their flocks of goats, that 

 produced such effects. Just as Tsetse-flies attack cattle, so do the 

 Donderobo flies chiefly attack donkeys and goats, more rarely sheep, but 

 never cows. On the third day the animal that has been stung is already 



X 



