SUPPLEMENTARY REPORT. 49 



to place of Ghssina palpalis, the flies frequently travelling in the carriages. It is to 

 be supposed too that they there accompany cattle brought in open trucks through 

 the fly areas in the north for slaughter in the south. 



Expulsion of the flies might possibly be efiected through the elimination of the 

 larger trees favoured by the flies as resting places. Much of the fly area does not 

 seem favourable to the growth of these trees, so that they are comparatively few and 

 far between, and the measure is not so impracticable as might be anticipated. 

 Baobabs on account of their gigantic girth would offer the main difficulty, but this 

 could doubtless be overcome by the use of explosives. 



A more ideal method would of course be the felling of all large trees and their 

 utilisation as artificial breeding places, but the disadvantage would be the difficulty 

 of discovering all at such times as it became desirable to collect the pupae. 



Parasites. 



I have endeavoured within the last few days to ascertain further whether Mutilla 

 glossinae is included among the Mutillids found in the Proclaimed Area. A large 

 series of species of this family has been obtained over a stretch of sandy soil about 

 half a mile long and 200 to 300 yards broad surrounded on all sides by lower lying 

 ground, now swampy. M, ghssinae is not among these, but the astonishing number 

 of various Mutillids found doubtless indicates the modifying effect of ground water- 

 logged in the wet season on the distribution of these insects. 



Three female M. ghssmae, which emerged from wild morsitans pupae on 5th, 

 11th and 19th October respectively, were paired with a male on the day of emergence 

 and kept in jars each containing twenty pupae deposited by captive flies between 

 20th October and 8th November, 



Three offspring of female A, all females, emerged from the pupae between 7th and 

 11th December. Five offspring of female B, two males and three females, emerged 

 between 8th and 20th ; and three, a male and two females, the offspring of female C, 

 emerged between 19th and 24th December. Tsetse have emerged from many of the 

 pupae, but there still remain some which may yield more Mutillids at another season. 



Though this breeding experiment confirms previous results I am not of opinion 

 that it affords adequate evidence as to the fertility of the parasite, for the females 

 did not thrive in captivity, as did others early in the dry season, and in consequence 

 various other experiments of a like character were brought to a premature close. 

 A far lower percentage too have emerged latterly from pupae found in the vicinity 

 of Monlcey Bay. 



Various captured specimens of the Bombyliid fly, Thyridanthrax abruptus, Lw., 

 were placed between 19th and 30th November in jars containing pupae deposited 

 by captive flies between 7th and 14th November. On 20th December one of the 

 offspring of these flies emerged, and between that date and 24th three more. This 

 Bombyliid is therefore a direct parasite of morsitans pupae. 



The flies are by no means easy to deal with in captivity, for they dash themselves 

 wildly against the sides of the jar, so that they soon lose all the hairy covering of the 

 body and the wings break off short, but some feed freely and can then be kept ahve 

 up to a week. 

 (C250) D 



