266 GLOSSINA PALPALIS [CH. 



the results also explain the necessity to the flies of a humid 

 atmosphere such as the neighbourhood of shady rivers. 



The length of life of the fly is very considerable. In the 

 laboratory, Kleine observed one female to live for 227 days, 

 which is the record up to the present. Carpenter has recently 

 tried to ascertain the length of life of the fly by marking large 

 numbers and then liberating them in order to see how long 

 marked specimens could be caught at the same spot. One 

 female was recaptured 182 days and one male 199 days after 

 they had been marked. 



Reproduction. As in all tsetse-flies G. palpalis does not 

 lay eggs, but deposits the fully formed larva, after it has under- 

 gone a period of gestation within the uterus. 



Fig. 69. Glossina palpalis. Female in the act of parturition. (X4.) (After 

 Newstead.) 



The first larva is dropped three to four weeks after copula- 

 tion, the gestation being exceptionally long because the uterine 

 glands are not well developed. Afterwards larvae are dropped 

 at intervals of nine to ten days, so long as the temperature 

 remains at about 25° C. and the fly has abundant food. Roubaud 

 found that one female produced eight larvae in 13 weeks ; 

 when dissected, the uterus of this fly contained one egg, but 

 the ovary was empty. It is possible that the female may go 

 on producing larvae for a very considerable period, but the 

 observations on this subject are too few to be of any use. 

 Although in the laboratory the fly breeds all the year round, 

 it is probable that in nature the seasonal effects may be very 

 great, for in cold weather the tsetse does not bite readily and 

 food has a marked influence on its reproductive activities. 

 The female feeds readily at the commencement of gestation, 

 but as the larva approaches maturity ceases to feed until it is 

 born, when she again becomes hungry. 



