152 DISEASES DUE TO PROTOZOA 



Probably all the species are capable of carrying trypanosomes. 

 We will give a few features of the two most important. 



GLOSSINA MORSITANS. 



This species was known first as a result of the writings of 

 Livingstone and Cummings. 



Habits. 



It inhabits dry thorny scrub, which covers large areas of Central 

 Africa. It is not found along the river banks or other water courses ; it 

 dislikes water. It requires shade and is never found on the open plains 

 exposed to the tropical sun. It begins to bite soon after sunrise on a 

 fine day, usually disappears at mid-day, comes out again towards sun- 

 set and is then very active. 



In rain and wind they will remain hidden. 



They are most numerous towards the end of the rains. 



Food. 



Of 500 flies examined in Nyasaland the intestines contained mam- 

 malian blood, chieflv antelope's, in 57 per cent, of cases. 



They never suck fruit juices like the mosquitoes. 



They feed once during 30-70 hours. 



When feeding, the fly fully distends itself in I to i minute after it 

 has punctured the skin. A male can absorb it, times its body weight 

 of blood and a female r6 times its weight. In two or three minutes 

 after the feed, minute d'rops of digestive fluids are exudated from the 

 anus, a process which continues at the rate of 2 per minute for 20 

 minutes. Some hours later a thick brown excrement follows and the 

 abdomen becomes markedly reduced in size. 



Reproduction. 



All Glossinre are pupiparous and in this differ from most of the 

 Diptera. The female produces one white-yellowish larva once in ten 

 days. This is retained in the oviduct until fully grown. When born 

 it creeps into the soil or amongst the leaves and debris and within a 

 few hours has changed to a hard, black puparium. The adult fly 

 emerges in about 23-60 days according to temperature. The female 

 generally chooses the under surface of a tree for this purpose, generally 

 near a native path or a game track so as to facilitate the mother's 

 obtaining food for her young and herself. 



GLOSSING PALPALIS. 



These are widely distributed. They are lovers of water and are to 

 be found frequenting the edges of rivers, lakes, ponds, water holes in 

 banks where there is clear water and plenty of shade, thick under- 

 growth with high trees and dense jungle. 



They are never found on open beaches backed by grassy plains even 



