44 NATURAL HISTORY OF GLOSSINA PALPALIS 



males that had been marked between April 1st and 6th. 

 This gives a minimum duration of life of 247-253 days 

 for the male. A female fly caught again on August 17th 

 had been marked between April 8th to 13th, so it had 

 lived at least 126 to 131 days. This was not quite so 

 long as the longest Jinja period (182 days). Thus it was 

 established that palpalis can live for several months, but 

 the probability is that it does not survive a second dry 

 season. In both experiments the last flies were caught 

 at a time when the relative humidity of the air was 

 low. 



Both at Jinja in 1910 and on Bugalla in 1911-12 care- 

 ful meteorological data were kept, and the influence of 

 climatic conditions upon the total number of flies that 

 were caught per boy per hour was found to be very 

 interesting (see Chart III). 



In those days the male catch alone was not used as a 

 means of estimation. 



The number of flies caught at Jinja on the mainland 

 varied directly with the relative humidity of the atmosphere, 

 which itself varied during the period from the beginning 

 of August to the end of January from 63 per cent, to 

 76 per cent, (see Chart II). 



On the other hand, on Bugalla Isle no such relationship 

 could be made out, but here the relative humidity only 

 varied from 77 per cent, to 72 per cent, during a continuous 

 period of twelve months. On the mainland there was a 

 very decided inverse relation between the number of 

 flies caught and the temperature. In the hotter (and drier) 

 months there were fewer flies. This did not seem to be 

 so markedly the case on Bugalla, probably because the 

 humidity of the atmosphere was so much more constant 

 on the island that a higher temperature did not necessarily 

 kill oflt the flies. 



In this fact may be the explanation of the occurrence 

 of flies on Nsadzi at the west end, where there was so 



