294 THROUGH ANGOLA 



comparatively easy to channel the watercourses 

 and prevent the breeding of malarial mosquitoes. 



Of the tsetse flies, two varieties at least are 

 found in Angola ; the Glossina palpalis, or fly 

 which conveys a trypanosome germ, the cause 

 of sleeping sickness to human beings, and the 

 Glossina morsitans, which carries an allied trypano- 

 some and the dreaded fly disease to animals. In 

 Rhodesia the Glossina morsitans has now' been 

 found to carry the sleeping sickness germs as well, 

 and several of the varieties of Glossina flies which 

 may yet be found in Angola can convey trypano- 

 some disease to animals. 



The whole tsetse or Glossina family are thus 

 dangerous or suspect, and it is advisable to recog- 

 nize and avoid them. 



The tsetse fly is nearly twice the size of a house 

 fly, has a short thick proboscis, wings which 

 project beyond the body and when folded overlap 

 like the blades of a pair of scissors. The Glossina 

 palpalis is dark in colour ; the 'Morsitans lighter, 

 with indistinct grey and black bands on IN 

 abdomen. 



All tsetse flies have a darting flight, appear ard 

 disappear quickly, and preferably at hick movi no- 

 objects, They are viviparous, depositing iVlv 

 formed lavvre which turn into pupre within nn hour. 

 though the pupa itself takes three weeks or more 

 to become a fly. 



The Palpalis lives near streams and lays eggs 

 under shady trees and bushes close to the water : 

 while the nest of I he ^lorsiianx is in dry forest 

 country, usuallv at the foot of n Jarp-e tree, 



