GLOSSINA INVESTIGATIONS IN NYASALAND. 



251 



possible that this may conduce to it. Latterly, therefore, it has been my practice 

 to keep such females apart from the males, the results obtained justifying the 

 correctness of the conclusion. It often happens also that a male will become securely 

 locked to a recently dead female, and Dr. J. B. Davey, of the local medical service, 

 informs me that he has repeatedly witnessed a similar occurrence. 



These facts undoubtedly indicate the necessity for the pregnant female to seclude 

 herself, when once fertiUsed, from the further attentions of the males ; hence the 

 unequal proportion of the sexes among captured flies. 



If this supposition be correct, a comparison of the proportionate numbers of the 

 sexes caught during the breeding season, and when breeding is not going on to so 

 great an extent, should yield evidence bearing on the question. There are not, so 

 far as I am aware, statistics dealing with the breeding habits of the fly in Nyasaland, 

 and as the seasonal conditions are probably different from those of Rhodesia, an 

 examination of such data obtained there is not likely to shed much light on the 

 question here. I am, however, sure that the flies just now in the early dry season 

 [beginning of June] are breeding more freely than they did when the rains were on 

 in February, and a consideration of the relative proportion of the sexes taken over 

 a given period of time at the two seasons does afford some slight evidence in support 

 of the supposition, the females in February forming 15 per cent, of the total captures, 

 and in May 5 per cent. The actual figures are given in the following table : — 

 Table showing Proportion of Sexes in captured G. morsitans. 



Locality. 



Date. 



Males. 



Females. 



Kemarks. 



Lingadzi 







3.ii.l5 



4.ii.l5 



5.ii.l5 



6.ii.l5 



7.ii.l5 



8.ii.l5 



10.ii.l5 



ll.ii.l5 



12.ii.l5 



13.ii.l5 



15.ii.l5 



16.ii.l5 



150 

 129 

 231 

 111 

 142 

 128 

 130 

 183 

 163 

 116 

 118 

 186 



16 

 19 

 22 

 24 

 32 

 21 

 25 

 35 

 23 

 11 

 12 

 24 



Wet season. 





Total . . 



1,788 



264 15 % (almost) 

 of females. 



Monkey Bay . 







11.V.15 

 12.V.15 

 13.V.15 

 14.V.15 

 16.V.15 

 17.V.15 

 18.V.15 

 21.V.15 

 22.V.15 

 23.V.15 

 24.V.15 

 26.V.15 



143 

 282 

 136 



76 

 113 

 103 

 128 



80 

 215 



99 

 152 



71 



5 



28 



4 



11 



10 



3 



5 



4 



5 



5 



4 



0' 



Dry season. 



Total 



1,598 



84 



/o 



