GLOSSINA INVESTIGATIONS IN NYASALAND. 265 



both of morsitans and of brevipalpis, never more than three or four of each. But on 

 removing the low, thickly growing vegetation at a spot well sheltered by the foliage 

 of the large trees, I obtained in the course of a two days' search over an area about 

 twenty-five yards square no less than 507 pupa-cases and seven living pupae. 

 This spot differed in regard to soil and vegetation in nowise, so far as I could 

 ascertain, from the rest of the neighbourhood, but it was traversed by a path along 

 which game is evidently in the habit of passing to and from the water, and moreover 

 it is close to the edge of a sandy bank (the original edge of the lake, which is gradually 

 receding), and I imagine it to be probable that beasts may loiter there as a measure 

 of caution before descending into more open country, as a result of which replete 

 female flies, incapable of prolonged flight, would shelter there. More pupae have 

 been found in similar situations, 109 pupa-cases in one place, and 4 pupae and 54 

 cases in another. I expect that the small number of living pupae hitherto found 

 may be explained by the breeding season being over. As with the pupae of morsitans 

 there is some variation in regard to size. 



Some of the flies have emerged from the pupae ; all, as was to be expected, in the 

 late afternoon ; one, a female, attempting to do so tail end first, a condition not 

 unfrequently seen also with morsitans. 



Small round holes, indicating probably the escape of larger Chalcids, were seen 

 in four pupa-cases only out of a total of 737. No other evidence of parasitism was 

 obtained by an examination of the cases, but on placing one of the pupae in a jar 

 containing a female Mutilla glossinae with morsitans pupae, the Mutillid unhesitatingly 

 bored a hole in the usual way and oviposited in it. 



