838 



THE DIPTERA 



coloured flies, with the wings closed flat over one another, and 

 projecting considerably beyond the abdomen when at rest, with an 

 anterior projecting proboscis, beyond which the palpi slightly extend, 

 and in which they are ensheathed. Base of proboscis bulbous. 



This is the genus of the tsetse-flies, a name probably derived 

 from the noise which they make when flying, and now used in a 

 generic sense. They were first named by Wiedemann from G. longi- 

 palfis, brought from Sierra Leone by Adam AfzeUus, and in the same 

 year Robineau-Desvoidy named another species from the Congo 

 Nemorhina falpalis. Their bites have been long known to be 

 dangerous to animals, but it was not till Bruce showed that they 



Fig. 429. — Glossina palpalis : Female. 



were the spreaders of Trypanosoma brucei and the cause of the 

 disease nagana in horses, etc., that they received much attention. 

 The interest in them became vastly greater when in 1903 Bruce 

 and Nabarro showed that they were the spreaders of T. castellanii 

 and especially when Kleine showed that the transmission was not 

 mechanical. 



The genus is confined to tropical Africa and Arabia. 



Morphology. — ^The points in the morphology to which attention 

 should be paid are as follows : — 



The eyes are large and bare, and between them the vertex is 

 depressed, and at its back carries ocelH. In front a deep facial pit 



