GLOSSINA INVESTIGATIONS IN NYASAL AND. 



41 



But very different figures are obtained if captures of flies which have settled near 

 to the possible host are included. As the easiest method of securing these an umbrella, 

 under which the flies will settle at any time during the day, was carried, and a series 

 of captures was made daily from 7 to 11 a.m. and from 3 p.m. to dusk by two boys, 

 one carrying the umbrella and the other catching the flies, while at the same time 

 two other boys a short distance away took flies in the usual way off each other. 

 The results tabulated below are striking : — 



Flies caught 7 to 11 a.m. 



Flies caught 3 p.m. to dusk. 



The proportion of females captured under an umbrella works out therefore at about 

 35 per cent, for the morning and 35 per cent, for the afternoon, whereas when captures 

 were effected in the usual way the percentage fell to 10 for the morning and 9 for the 

 afternoon. None of the females showed evidence of having fed recentlv. 



During the heat of the day, from about 11 to 3, the numbers of morsitans on the 

 wing are much diminished, as is shown by data given in a subsequent paragraph, 

 but I have never found that, as stated by Lloyd in his notes on the species in the 

 Luangwa valley (Bull. Ent. Res., iii, p. 235), they then disappear except in deep shade, 

 for they have been obtained here on the hottest days with a still atmosphere, and 

 isolated flies may even be encountered over dambos and cleared spaces in the fly areas. 

 The idea then suggested itself to me that an investigation of the sheltering media used 

 at this time by the flies might throw further light on the special habits of the females, 

 seeing that though the sexes emerge in about equal proportions from pupae both 

 bred and obtained iij natural breeding places, the males still exceed the females 

 even when the flies are captured by a special method. 



