114 



In captivity, pairing took place soon after emergence and oviposition 

 began about two hours later in pupae believed to be parasitised by 

 M. glossinae. Nine females oviposited in pupae of G. morsitans, the 

 cocoon of M. glossinae being present in every case except one ; 22 males 

 and 58 females emerged. In those instances in which definite data 

 were obtained, the period between oviposition and emergence varied 

 from 28 to 32 days, the greatest number obtained from a single 

 puparium being nine. In several cases Mutilhds emerged from pupae 

 into which E. tarsatus had inserted its ovipositor and in two cases 

 tsetse-flies emerged from such pupae. A few large Chalcids, Stomato- 

 ceras spp., were obtained from pupae found in the neighbourhood of 

 Monkey Bay between 7th April and 2nd June, but were absent from 

 pupae in the proclaimed area. These Chalcids may be hyperparasite of 

 31. glossinae, since specimens of the latter were present in some cases, 

 but more probably are primary parasites of Glossina which develop 

 more rapidly than M. glossinae and may incidentally attack the larva 

 of this species. 



In considering the relation between tsetse-flies and the larger animals, 

 it has been observed that an abundance of flies is correlated with the 

 actual or recent presence of game in any given area. The high develop- 

 ment of the sense organs connected with the antennae renders the fly 

 able to detect its food from a long distance. A meal is required every 

 five or six days, hence the presence of a large number of game animals 

 is not essential. Part of the food is derived from baboons which occur 

 in all districts in which the fly has been studied. Bare-necked birds, 

 such as vultures, may furnish food material to a shght extent, but the 

 presence of feathers in other forms is beheved to render feeding veiy 

 difficult. The scarcity of reptiles appears to negative the supposition 

 that these animals may furnish a blood supply. Small Lacertidae 

 are probably too active to be of material value as a source of food. 

 Tests wdth toads and tree-frogs gave negative results. It is however 

 pointed out in an editorial note that the evidence that G. morsitans 

 does not normally feed on non-mammalian blood is less conclusive than 

 would appear from these statements. The preference of G. falpalis 

 for reptilian blood under natural conditions is also noted. This 

 preference is contrary to laboratory results, which cannot therefore be 

 rehed upon in considering the natural food of these flies. 



Artificial breeding places have been constructed at Rifu, in the 

 proclaimed area and near Monkey Bay, the object being to determine 

 which trees are most favoured as resting-places. Various species of 

 trees were felled and in some of the breeding places the natural soil 

 was replaced by soil from natural breeding places ; in others the earth 

 was mixed with fragments of rotting wood and bark, with earth from 

 termitaria and with antelope droppings. Natural breeding places 

 in both these areas were eliminated. The effect of bush fires on the 

 distribution of the fly in certain districts in the proclaimed area was 

 observed. A marked decrease in numbers was noted in the burnt 

 area, but pupae sufficient to repopulate the same were found under logs 

 untouched by the fires. Flies were abundant in a neighbouring district 

 and this abundance was undoubtedly the result of the fire and the 

 driving away of the game. Systematic burning of grass is not likely 

 to be of material value in controlhng the fly, as it only occurs in patches 

 over much of the fly country, and the fires therefore fail to spread. 



