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SOME FURTHER NOTES ON THE TSETSE-FLIES OF NYASALAND. 

 By W. A. Lamborn, M.R.C.S., L.R.C.P. | 



Glossina morsitans. 



A fortunate stay of a few days in July 1919 at Fort Johnston, Lake Nyasa, 

 wMle waiting instructions, enabled the writer to proceed to the village of Mzeze 

 near the Livingstonia Peninsula, where in 1914-15 some work was carried out on the 

 various insects parasitic on the puparia of this fly. 



The success at that time of the various parasites, especially Mutilla glossinae, 

 Turner, as judged by the numbers of their cocoons found in old puparia of the fly and 

 bred from recent ones, had been phenomenal, and so the chance, though one lasting 

 only a few hours, of ascertaining the progress made by these insects in the course of 

 the three subsequent years was a very welcome one. 



The early rainy season was quite similar in character to that of 1915, when long 

 series of the flies had readily been captured in the district, on passing through which 

 one had been constantly harassed by a buzzing swarm. Far different was one's 

 present experience, for though the journey was made on a cycle, which attracts more 

 flies than a pedestrian, none at all appeared, and it was only on the following day 

 that a single specimen was taken in the course of a hunt for puparia. Local natives 

 agreed as to the diminution in numbers of the flies thereabouts without there being 

 any f alhng off of game, and added that the pests had now become more numerous to 

 the north, a statement substantiated by personal experience a few weeks later on. 



A gang of six boys, who had on a previous occasion worked as puparia collectors 

 and were therefore experts, were got together to assist again in collecting puparia, 

 and the results were confirmatory ; for though two days were devoted to the search, 

 only 107 old puparia and 15 new ones were forthcoming, mostly from the artificial 

 breeding places designed in 1915. Examination of the old puparia showed that nine 

 definitely had been destroyed by MutilHd parasites, but it was not possible 

 to determine with certainty the full extent of the parasitism either by this species 

 or others, owing to the age and broken condition of many of the puparia. Of the 

 fifteen new puparia three only afforded flies, a male on 23rd August, a female 

 on 1st September, and another female on the 4th. Five yielded Mutilla glossinae, 

 two males on 17th September, one male on 18th, and one of each sex as long after 

 as 29th. The remaining puparia all died, possibly as a result of the vicissitudes of 

 temperature to which they were exposed, for they were taken on a month's foot 

 journey in the uplands of Angoniland, at an average elevation of from 3,000 to 

 4,000 feet, hot days being generally succeeded by chilly nights. 



Whereas in 1915 at Mzeze parasites would be readily obtained, at Domira Bay 

 none at all were either captured or bred out, this being about fifty miles to the north 

 and separated from the Mzeze area by the south-west arm of Lake Nyasa. No 

 opportunity of visiting the area at Domira Bay occurred, but in September 1919 

 a visit was made to another section of it, at Kotakota, about forty miles north of 

 Domira Bay, where between the 6th and 10th of the month hundreds of old 

 G. morsitans puparia, and sixty-five new ones were obtained. None of these old 

 pupa-cases showed the Mutilhd cocoons, nor did any of these parasites emerge from 



