THE GREW ZEBRA 155 



done. The tse-tse has only two wings, the pos- 

 terior pair being represented, as in the common 

 housefly, by rudiments or " balancers." As if to 

 compensate for the loss of the hind wings, the 

 anterior pair are long and well developed, pro- 

 jecting, when closed, considerably beyond the end 

 of the body. The tse-tse has a characteristic 

 buzz, probably produced by the rapid vibration of 

 the balancers ; the chief interest attaching to this 

 terrible insect, however, centres in its proboscis, 

 which consists of a hollow stylet, protected by an 

 adpressed palpus, on each side, and furnished at 

 its base with a bulbous expansion. The tse-tse 

 thrusts the central stylet into the skin of the 

 victim, sucking up the blood like an ordinary 

 mosquito in England. Although happily innocuous 

 to man, the stab of this winged terror is fatal to 

 nearly all domesticated animals. 1 The victim in a 

 few days begins to sicken : then, with running 

 eyes and nostrils and staring coat, the unfortunate 

 animal rapidly goes down hill, struggling about in 

 a state of emaciation for a few weeks three 

 months at most and eventually dying exhausted. 

 The blood for a short time before death is found 



i It was formerly thought that the bulb situated at the root of 

 the proboscis was a poison gland : such, however, is not the case, the 

 tse-tse being harmless in itself. Frequently, however, minute para- 

 sites, derived from a previous host, adhere to the proboscis 01 the 

 tse-tse : these are introduced accidentally when the fly begins to suck 

 its next subject. If this second host be susceptible, the parasites, 

 which rapidly multiply in the blood by longitudinal division, soon 

 kill it. 



