68 



on a goat with avidity a few minutes after it ; and it is usual to be 

 much assailed by such flies immediately they are released." 



No female flies were recaptured, but, between 7th and 22nd December, 

 inclusive, 14 marked males were taken, four of them near or at 

 Chunzi, the remainder at Lingadzi. "Evidence has therefore been 

 obtained," continues Dr. Lamborn, "of 10 flights of five miles and of 

 one flight of no less than 10 miles back to the locality from which the 

 flies were originally taken, and, in the case of three other flies, of 

 flights tending to show that they were on their way back also. The 

 flies recaptured were all taken at the fringe of the fly area, where, on 

 account of the greater probability of meeting with them, the collectors 

 had instructions to work. The country which they necessarily 

 traversed is all well-wooded and without open spaces, and though 

 careful search was made for released flies in directions away from the 

 main fly area, none were obtained. No flies were fed previous to 

 release." 



In three subsequent series of experiments by Dr. Lamborn in con- 

 tinuation of the foregoing, the system adopted was the same as before. 

 Dr. Lamborn writes (83) : "In passing from a morsitans area into 

 country apparently free from them, whether bush or open country, it 

 has always seemed to me that the same tsetses which have been 

 hovering round continue to follow for a considerable distance. With 

 the object of deciding whether such flies do really attend one and are 

 not chance new-comers, a series of experiments have been conducted, 

 consisting in liberating marked flies at a definite point, and then after 

 a walk to various distances capturing all those in the immediate 

 neighbourhood/ ' 



In the first series of experiments, " conducted in the neighbourhood 

 of Domira Bay," 120 male flies were released, and 14 were recaptured 

 at a distance of two and a half miles from the starting-point. 



In the second series, " carried out at Monkey Bay," 600 males were 

 released, and 83 recaptured at distances varying from half to one and 

 a half miles. 



The third series of flight experiments was made in the proclaimed 

 area, and consisted in " releasing marked male flies, as before, at a spot 

 two miles south of the Lipimbi river, at an altitude of 1,950 ft., and 

 recapturing as many as possible in the region from which they had 

 been removed, namely Lingadzi, about five miles distant in direct line, 

 with an altitude of 1,700 ft." " In making these experiments," 

 writes Dr. Lamborn, " every precaution was taken to guard against 

 possible fallacy. The flies were liberated by placing the cage in a 

 tuft of grass before opening the door, by which means it is possible 

 for the person conducting the experiment to get away to a distance 

 before any flies are able to follow. In no case did the person releasing 

 them return to the tsetse area, and there was very little probability 

 of any flies returning on the backs of chance passers-by." In all, 1,776 

 male flies were released at Lipimbi River, on various dates from 3rd 

 February to 16th February 1915, inclusive, and from 4th February to 

 17th February 17 flies were recaptured. 



Flight experiments conducted by Dr. J. J. Simpson (144) in the 

 Gold Coast, with marked individuals of G. tachinoides, yielded the 

 following results : The greatest distance covered by a single fly was 

 four miles ; all seemed to return to water, as none were caught at a 

 greater distance from the river than the points where they were 

 liberated ; if streams intervened between the place of liberation and the 

 river, the flies made their way down stream to the river ; if the stream 



