XVI] REPRODUCTION 285 



trees, such as are at that time of the year practically confined 

 to the banks of rivers, pools, and vleis, dry or otherwise on the 

 surface. Generally the soil is easily worked, and often humus 

 is abundant, and the drainage is usually good. The selection 

 of a well drained situation may not seem necessary in the dry 

 weather, but the instinct to select such would doubtless be of 

 great value, when the pupal period extends into the rains. 

 During the wet weather it is probable that the young are 

 deposited more generally through the bush." 



Mr R. S. Harger, late of North Eastern Rhodesia, in a letter 

 published in The Field states that he had often watched 

 G morsitans depositing its eggs (= larvae) in the damp soil, 

 thrown up by the digging of a trench round his tent. 



In captivity, when the freshly laid larva is placed on 

 powdered earth it immediately commences to burrow until it 

 is from one to two centimetres below the surface, when it at 

 once proceeds to pupate. Apparently the larvae are capable 

 of secreting a slightly viscid fluid, for in glass tubes they were 

 often observed to adhere to the side and Kinghorn suggests that 

 the purpose of this fluid is to gather the earth around the pupa. 



As in all species of Glossina, the duration of the- pupal 

 stage varies according to the temperature. In Rhodesia, at a 

 temperature of 15 to 25 C., Kinghorn found that the pupal 

 period varied from 47 to 53 days. On Lake Victoria, according 

 to Fischer, the period lasts on an average from 35 to 40 days, 

 whilst Roubaud, in the Upper Dahomey, found that at a tempera- 

 ture of about 32 C. the duration of the pupal stage was only 

 23 to 28 days. Lloyd, at Nawalia, obtained similar results, 

 for at temperatures ranging from 17 to 28 C., the average 

 duration of the pupal period varied from 22 to 51 days. 



As in the case of G. palpalis, intra-uterine pupation has been 

 observed occasionally. 



G. MORSITANS and Disease. 



G. morsitans is known to be the carrier of more trypanosome 

 diseases than any other species of Glossina. 



In the first place it has been proved to be the main, if not 

 the only, carrier of T. rhodesiense, the pathogenic agent of 



