TSETSE FLY 165 



with a sober brownish or brownish-grey coloration. 

 When at rest the two wings are completely super- 

 imposed, like the blades of a shut pair of scissors ; 

 and this feature readily serves to distinguish the genus 

 from that of all other blood-sucking flies, and is of 

 great use in discriminating between the tsetse and 

 the somewhat nearly allied Stomoxys and Hcema- 

 topota. 



The tsetse flies rapidly and directly to the objects 

 it seeks, and must have a keen sense of smell or sight, 

 or both, making straight for its prey, and being most 

 persistent in its attacks. The buzzing which it pro- 

 duces when flying is peculiar, and easily recognized 

 again when once heard. After feeding, the fly emits a 

 higher note, a fact recalling the observation of Dr. 

 Nuttall and the present writer on the note of Ano- 

 pheles, in which animal they observed that, ' the 

 larger the meal, the higher the note.' The tsetse 

 does not settle lightly and imperceptibly on the 

 sufferer as the Culicidae do, nor does it alight slowly 

 and circumspectly after the manner of the house-flies, 

 but it comes down with a bump, square on its legs. 

 Like the mosquito, the tsetse is greedy, and sucks 

 voraciously. The abdomen becomes almost spherical, 

 and of a crimson red, and in the course of a few 

 seconds the fly has exchanged the meagre proportions 

 of a Don Quixote for the ampler circumference of a 

 Sancho Panza. There is a good deal of discrepancy 

 between the reports of the various sufferers as to the 

 pain of the bite. No doubt different persons are very 

 differently affected, and suffer to very varying degrees. 

 Unlike so many of the blood-sucking Diptera, in which 

 the habit is confined to the females, both sexes of 

 Glossina attack warm-blooded creatures. 



The fly always seems to choose a very inaccessible 

 portion of the body to operate on between the 

 shoulders in man, or on the back and belly in cattle 



