844 



THE DIPTERA 



creepers, tall grass, cane-break tangle, and herbaceous plants. Tall 

 trees alone will not afford the protection necessary for the fly unless 

 they overhang the water, or their foliage reaches so low as to mix 

 with the undergrowth. 



The fly is, however, not met with behind a wide strip of papyrus, 

 though it may be found on its water edge. This is explained by 

 Bagshawe on the grounds that papyrus grows best in shallow water, 

 which means that the ground is swampy, a condition which prevents 

 the fly from depositing its larvae. From a resort such as this a fly 

 can travel for feeding purposes, or be carried by attraction or 

 artificial means. It appears probable from Bagshawe's experiments 

 that a single flight will not reach 70 to 80 yards, but flies can be 

 carried to almost any distance by the agency of boats and floating 

 islands of papyrus. Human traffic also increases the dissemination 

 of the fly, as it is apt to pursue human beings for considerable 

 distances. 



Female flies appear to travel farther in search of food than males, 

 probably because they more urgently require it. Bagshawe suggests 

 that this can be made use of in finding the breeding-grounds, where 

 he says plenty of males as well as females are to be found, while 

 females alone may be met with at some distance therefrom. The 

 feeding range, therefore, varies considerably. 



Flies bite mostly during the middle part of the day, and not so 

 much at dawn or in the late afternoon. 



According to Hodges, the chief conditions required for a breeding- 

 ground are loose, dry, friable earth, situate not more than 20 yards 

 away from the high-water mark of a stream, and protected from sun 

 and rain by the shade of trees and undergrowth. 



Such conditions are found on steep banks along lakes, rivers, 

 watercourses, etc., and the larvae are to be looked for at the bases 

 of shrubs and trees, in the undergrowth, and in earth-filled hollows 

 in tree-trunks and branches at no great distance from the ground. 



Bagshawe found the larvae principally at the roots of bananas 

 with scrub and water in the immediate neighbourhood; at the roots 

 of a shrub called Allophylkis, belonging to the Sapindaceae, especi- 

 ally in the dry season ; at the roots of large figs and of the wild date- 

 palm {Phoenix reclinata) ; while he also found a few pupae in dry earth 

 sheltered by overhanging rocks on wooded banks. 



The breeding season appears to be at the commencement of the 

 rains, as Bagshawe generally found empty pupal cases in the dry 

 season. 



The pupae apparently have their enemies which eat them. These 

 are minute winged insects probably belonging to the Chalcididae, 

 though this is not definitely known. 



Pathogenicity. — Glossina palpalis is the carrier of Trypanosoma 

 castellanii, and G. morsitans of T. rhodesiense, both of which are 

 the causes of sleeping sickness in Africa. 



Classification. — Newstead in 191 1 revised the genus Glossina, and published 

 a classification based on the male genital armature. This is a very excellent 



