258 W. A. LAMBORN. 



Some few pupae have been found under trees in accumulations of dead leaves 

 on the surface of the ground, but so few, that this again is probably purely 

 accidental. Pupae in such situations seem to stand little chance of survival, 

 for repeated experiments made by exposing bred ones in similar surroundings in 

 the hope of getting them parasitised, have resulted in the loss of the majority, some 

 undiscovered insects, possibly cockroaches, which one finds not infrequently, having 

 eaten out the pupal contents. 



As has already been pointed out by workers in Rhodesia, pupae may be deposited 

 in cavities in dead limbs of trees, a certain amount of soil, the result of the 

 admixture of earth originally brought by termites with wood debris, being invariably 

 found in such situations (Plate v, fig. 2). 



The question of soil in the various breeding places has been studied, but no special 

 sort seems to be favoured, the chemical constitution being immaterial, so long as 

 the soil is friable. All the trees also, in relation to which pupae have been found, 

 have been carefully examined with a view to ascertaining whether one species 

 more than another is favoured by the fly. In the majority of cases decay has been 

 so far advanced that the determination has been out of the question, but in 

 48 instances specimens of the foliage, representing at least fourteen species, have 

 been obtained and are available. In five cases a few pupae have been found under 

 the shelter of a fallen Borassus palm. 



Further study of the question has shown that the presence of a dead tree is by no 

 means essential, for in certain parts of the Monkey Bay district breeding grounds 

 sheltered by overhanging rocks have been found, each yielding from two or three 

 to as many as ten pupae (Plate vi, fig. 1). 



Attention has been paid to the orientation of all these places, the conclusion 

 arrived at being that this is immaterial, all that is apparently required being that 

 the breeding places should be sheltered from the overhead sun. 



The conclusions arrived at from my study of the question are that the only 

 essentials inducing a female tsetse to select a particular spot are looseness of the 

 earth and shelter. In Nyasaland, as in Rhodesia, the situations most favoured are 

 near game and native paths, and near water-holes (Plate vi, fig. 2), whereby the 

 newly emerged fly is in the most favourable situation for obtaining food in the 

 shortest possible time after emergence. Beyond this, the choice of a site by the 

 parent fly is not in my opinion influenced by any special type of soil or of vegetation. 

 The insect fauna in breeding places has been studied as digging has proceeded. 

 It is never very numerous, the only frequent occupants of such places being small 

 blackish Myrmicine ants [Pheidole megaceyhala, F,] and the larvae of ant-lions. 

 Small cockroaches and their oothecae are not uncommonly found, and also the 

 pupa-cases of the large Ponerine ant, Paltothyreus tarsatus, F., which insect is 

 frequently seen transporting its pupae and probably deposits them in such a situation 

 as being sheltered. 



It is by no means uncommon also to find small lizards and geckos, which doubtless 

 take some toll of pregnant and newly emerged fl.ies. But the fly is able to run with 

 such great activity for a short distance as to make it a matter of some difficulty 



