FLY-BELTS 167 



prey of the fly is undoubtedly the big game ol Africa, 

 including crocodiles, but they are not the only factor 

 in its distribution ; the nature of the land also plays a 

 part. There are the usual discrepancies in the accounts 

 of travellers, especially of African travellers, as to the 

 exact localities the Glossina affects ; but most writers 

 agree that the tsetse is not found in the open veld. It 

 must have cover. Warm, moist, steamy hollows, con- 

 taining water and clothed with forest growth, are the 

 haunts chosen. Even within the fly-belt there are 

 oases, due, perhaps, to an absence of shrubs or trees, 

 where no flies are. 



The' tsetse fly belongs to the family Muscidae, the 

 true flies, a very large family, which also includes our 

 house-fly, blue -bottle fly, etc. These flies, unlike 

 Anopheles and Culex, are day-flies, and begin to dis- 

 appear at or about sunset, a fact noted centuries ago 

 by Dante : 



' Nel tempo che colui, che il mondo schiara, 

 La faccia sua a noi tien meno ascosa, 

 Come la mosca cede alia zanzara.'* 



The practical disappearance as the temperature 

 drops has enabled the South African traveller to 

 traverse the fly-belts with impunity during the cooler 

 hours of the night. At nightfall the tsetse seems to 

 retire to rest amongst the shrubs and undergrowth, 

 but, if the weather be warm, it may sit up late ; and 

 some experienced travellers refrain from entering a 

 fly-belt, especially on a summer's night, until the 

 temperature has considerably fallen. 



The sickness and death of the cattle bitten by the 

 tsetse were formerly attributed to some specific 

 poison secreted by the fly, and injected during the 

 process of biting. It is now, largely owing to the 

 researches of Colonel Bruce, known to be due to the 



=•' ' Inferno,' xxvi. 26-28. 



