REPORT ON GLOSSINA IN NYASALAND. 65 



beset, for which reason I now invariably walk rather than cycle in a fly area. If one 

 stands still, such flies as may have been hovering around come to rest on objects 

 near by, frequently on a blade of grass, or they settle on the ground, resuming their 

 attentions immediately one is in motion again ; though if one remains still long 

 enough, as I have often found during a rest for lunch in the open ; the majority 

 gradually fly away. It is frequent, especially in the early evening, for flies to dog 

 one's footsteps, often for several miles, settling at intervals on the ground behind 

 and again and again catching up, an occurrence I have noticed repeatedly in respect 

 of men walking ahead of me and which I have then been able to verify in my 

 own case. 



The interpretation of these facts, and that several flies will often travel on a person 

 for considerable distances without attempting to bite, is not yet clear, but an 

 examination of 43 individuals taken off the ground on various occasions as they 

 followed showed that all were males, and it seems a reasonable supposition that 

 such flies may be lurking in anticipation of the advent of a female. No courtship 

 takes place, several males often making a simultaneous msh at the female on sight, 

 and one seizing her, pairing takes place in the air, the couple then settling. It is by 

 no means uncommon to take off natives in one's company a couple which have been 

 seen to pair, and several times paired couples have been taken by means of bird-lime 

 smeared on material borne on a native's back. 



With regard to the distance a fly will travel in pursuit of human beings, it has 

 been a frequent experience when crossing the open plain between the edge of the bush 

 and the lake to find fly with one all the way, a distance of 2J miles, and in passing 

 up in the dry season from Matumba's villages to Chunzi, a distance of 5 miles, the 

 path being rather devious, one was invariably accompanied by flies all the way. 



The distribution and numbers in a given locahty undoubtedly vary from day to 

 day, few being sometimes found where previous experiences have led one to expect 

 many, and vice versa. 



It has been a matter of surprise to find that G. morsitans heeds so little the heat 

 of the day, seeing that in my experience other species on the West Coast, palpalis 

 in particular, never expose themselves to the rays of the overhead sun, unless 

 compelled to do so. 



(C155) 



