136 



Chrysops, Stomoxys, etc., the forms found on the tsetse-flies were 

 not observed on any other insects. Specimens of these mites were 

 submitted to Mr. S. Hirst, of the British Museum, who . . . 

 expressed the opinion that they were larval forms of Trombidiidae, 

 and probably belonged to the genus Trombidium in its wide sense." 



As regards internal parasites of Tsetse-flies, the attention of investi- 

 gators should likewise be directed to the parasitic worms 1 (Nematodes), 

 and to maladies of protozoal, bacterial or fungoid origin from which 

 Glossina may suffer. Besides the various trypanosomes ( Trypanosoma 

 gambiense, T. rhodesiense, T. brucei, T. congolense, T. angolense, T. 

 cazalboui, etc.) of sleeping sickness and of Tsetse-fly disease of domestic 

 animals, which pass a portion of their life-cycle in Tsetse-flies, we are 

 already acquainted with others which so far appear to be peculiar to 

 these Diptera, and to undergo their entire development within them. 



If we were to succeed in discovering a parasitic disease affecting 

 Tsetse-flies, it might perhaps be possible to make pure cultures of the 

 virus, to render it more virulent or more effective, to propagate it, and 

 finally to arrive at results of practical value. 



Much of what has just been stated on the subject of enemies of Tsetse- 

 flies, based as it is on a small number of facts, is evidently highly 

 theoretical, and there can be little doubt that, among the investigations 

 to which attention has been drawn, the majority will not lead to any 

 result from the point of view of the destruction of Glossina. Never- 

 theless it is well to point out that this line of research may yet repay 

 serious attention. 



CHAPTER XIV. 



PROPHYLACTIC MEASURES. 



CLEARING. CATCHING AND SYSTEMATICALLY TRAPPING TSETSE-FLIES. 

 OTHER METHODS OF CATCHING AND DESTROYING TSETSE- 

 FLIES. ARTIFICIAL BREEDING PLACES. EMPLOYMENT OF 

 TSETSE-REPELLENTS FOR THE PROTECTION OF STOCK. OTHER 

 PRECAUTIONS FOR THE PROTECTION OF STOCK. PERSONAL 

 PROTECTION OF HUMAN BEINGS. DESTRUCTION OF BIG GAME. 



CLEARING. In the campaign against Glossina at the present time 

 efforts should especially be directed towards prophylactic measures, 

 or, in the words of Prof. E. Trouessart, the hygiene of the soil. 



Of these measures, clearing is by far the most important, and its 

 technique should be based on a study of the various questions relating 



1 Between September 1911 and March 1912, in dissecting some 300 specimens 

 of Glossina morsitans at Ngoa, in the Mpika Division, Northern Rhodesia, Mr. LI. 

 Lloyd found in two flies four examples of a parasitic Nematode, which were 

 identified by Dr. R. E. Leiper as immature forms of a species of Mermis, resembling 

 fairly closely those met with some years previously by Prof. Minchin in G. palpalis, 

 in Uganda. 



Dr. G. D. Hale Carpenter (25), on the other hand, in the course of his work 

 upon G. palpalis var. fuscipes in Bugalla I., Lake Victoria, Uganda, found 

 Nematodes in the abdominal cavity of 4 per 1,000 of the flies examined. 



Lastly, during the rainy season of 1911-12, the Mission Scientifique du 

 Katanga (116) observed at Sankisia (Belgian Congo) four cases of intestinal 

 parasitism of G. morsitans (two in wild flies caught in the savannah, and two others 

 in laboratory-bred specimens) by small Nematodes, which were likewise identified 

 by Prof. Gedoelst as larvae of Mermis. The largest of these worms measured 

 from 38 to 40 mm. in length, by - 25 mm. or 0'3 mm. in greatest breadth. The 

 wild flies did not seem to be suffering any ill effects, but one of the others 

 appeared to be somewhat affected. 



