FLIGHT AND BUZZING. 19 



and make a bold dash for supper at my expense. At that time 



of night they are easily caught, and almost invariably found 



their way into spirits of wine." 



Authorities agree in describing the flight of 

 Mode of flight, and , , „ . .< ■^ i x • l^ » r --i 



noise produced ttie Tsetse as "rapid and straight [30, 55j. 



by Tsetse when on Baines [55] says that "its sight and smell 



seem to be keen," and Foa [135] asserts that it 



" comes to its prey from a long distance, whether it is that its 



sight is keen or its sense of smell is exceptionally acute." * la 



the opinion of M. Foa the latter suggestion is more probably 



correct, since he has observed that the Tsetse " always comes up 



wind, and generally bites by preference on the leeward side." 



Colonel Bruce writes j : — " The Tsetse has a direct flight, 



flopping, if I may use the term, suddenly on the animal attacked, 



and is very pertinacious." On the completion of its meal, "when 



its abdomen is full of blood, its flight becomes heavy and it at 



once hides itself in order to digest its meal in peace " [135]- 



That the Tsetse owes its name to the sound produced by it 



when on the wing has already been pointed out in the note at 



the commencement of this chapter, | and its characteristic buzz 



has been referred to by various writers. Bradshaw [77] remarks 



that, " Its buzz is peculiar and not easily forgotten " ; while 



according to Livingstone [21], "Its peculiar buzz, when once 



heard, can never be forgotten." Captain Gibbons writes [152] ■— 



"The fly is frequently to be heard giving vent to the high 



pitched buzzing note which gives it a name . . . " ; and Colonel 



Bruce says,§ " The fly makes a loud buzzing sound when flying, 



but after its feed and at rest it emits a peculiar sharp, shrill 



note, probably caused by an action of the wings." || According to 



* It may be remarked that a large sense-organ, possibly olfactory in 

 function, is situated in the third joint of the Tsetse's antenna (See Pig. 9, 



p. m). 



t VUle Chapter VII., .Appendix A, p. 272. 



X See page 1. 



§ Vide Chapter VII., Appendix A, p. 272. 



11 The postprandial song of tlie Tsetse is more probably produced by 

 the thoracic stigmata or spiracles, or by the vibration of the thoracic- 

 walls. A large number of Diptera, especially Muscidse and Syrphidae 

 (Hover-flies, &c.), possess the power of thus producing a shrill sound 

 while at rest, with the wings closed. Cf. " Scricomyia borealis singing 

 while at rest" : Eev. E. N. Bloomfield, Entomologist's Monthly Magazine, 

 Vol. XVIII. (1881), pp. 159-160 : see also, A. H. Swinton, ibid. (January 

 1882), pp. 189-190, and J. Hellins, -ibid., p. 190. G. C. Bignell [Entomolo. 

 gist's Monthly Magazine, 2nd Series, Vol. II. (1891), p. 225) states that 

 Microdon ^mttabilis (Linn.), a somewhat rare British Syrphid, produces a 

 bumming noise when at rest and annoyed, by means of the vibration of tbo 

 halteros (the little knobbed organs found in all Diptera, except certain 



c 2 



