80 



swollen out like a balloon with blood in from thirty to forty seconds. In 

 captivity flies of this species show very little inclination to feed in very 

 hot and sultry weather, and this is also the case when the temperature 

 is abnormally low. Although continuing to bite and fly about ' for 

 some time after dark ' (Sanderson), G. brevipalpis appears not. to bite 

 during the actual night hours, and specimens kept in captivity in glass 

 cylinders were found in complete darkness to be perfectly still 

 (Stuhlmann). Like G. palpalis and blood-sucking flies in general, the 

 present species displays a predilection for dark-coloured animals and 

 surfaces. Stuhlmann states that he has frequently noticed that, when 

 a light- and a dark-coloured mule were moving side by side, only the 

 latter was attacked, and Sanderson writes : ' The flies bite through 

 dark clothes, but have never been seen to settle on white surfaces.' 1 



"As to the relation of G. brevipalpis to game, Davey observes that 

 wherever he met with this fly in Nyasaland ' game (antelope, warthog, 

 etc.) was abundant.' ' 



Writing of his experience of G. brevipalpis, G. morsitans and G. 

 pallidipes in Portuguese East Africa, Swynnerton (145) remarks : 

 " G. brevipalpis, as I found, attacks in the shade of the bush at any hour, 

 but does not fly appreciably outside its own thicket to do so except in 

 the early morning, after sunset and on dull or rainy days. Having 

 attacked, even in sunny weather, it completes its object of feeding or 

 riding, unless its victim emerges into the open. In this event it usually 

 leaves. In a special experiment that I carried out with the aid of a 

 lantern occasionally lit and turned on I found that both this fly and 

 pallidipes attacked right up to dark. Then every fly suddenly dis- 

 appeared. On moonlight nights they continue their attacks, and all- 

 three flies come to light, including firelight, and, once there, bite freely. 

 G. morsitans, I found, as have other observers, to be most active in the 

 rather warmer hours and least on cold or dewy mornings, but it too 

 attacked up to dark. It is probably dependent on shade to retire to 

 occasionally when blood and water are not available, for I captured 

 several male flies that had been resting under logs in the wooding 

 adjoining vlei edges frequented by male clusters. The frayed wings of 

 some showed that they had not just emerged." 



EXPERIMENTS ON THE TAKING OF FOOD BY TSETSE-FLIES. Investi- 

 gations and experiments upon the feeding of G. morsitans and G. 

 palpalis in captivity have been made respectively by Dr. Allan 

 Kinghorn and Mr. LI. Lloyd in Northern Rhodesia (1911-13), and 

 by Dr. J. W. Scott Macfie, West African Medical Service, at Zungeru, 

 Northern Nigeria (1911-12). 



While, as has just been stated, the subject of Dr. Macfie's experiments 

 for the purpose of studying the phenomena of feeding and digestion 

 was G. palpalis, the data obtained will apply, in their broad outlines, 

 to all the species of the genus. We give below excerpts from Dr. 

 Macfie's paper (93). 



FEEDING AND DIGESTION. " In considering the processes of feeding 

 and digestion of G. palpalis," writes Dr. Macfie, " it was found to be 



1 Swynnerton (145) says : " I was myself bitten by morsitans far less than my 

 natives, but this was presumably a matter of skin-colour and clothes ; Mabuzana, 

 living near the Mtshanedzi south of Gogoyo's, volunteered the information that 

 tsetses were specially attracted by a black coat. I said ' How do you know 

 that ? ' ' Because I have one ! '" 



