161 



The only species of Lyperosia of which the 

 Life-history, biology has yet been studied is the one just 



mentioned, the life-history of which has been 

 investigated in America by Biley and Howard.* According to 

 these authors, L. irritans oviposits on freshly dropped cow-dung ; 

 the eggs, which are " laid singly, and never in clusters, and usually 

 on their sides on the surface of the wet dung ; seldom inserted in 

 cracks," are light reddish brown in colour, irregularly oval in shape, 

 flattened on one side, and from 1.25 to 1.37 mm. in length, by 0.34 

 to 0.41 mm. in width. The newly-hatched larvce, which are pure 

 white, descend into the dung ; when full-grown the larvae are dirty 

 white in colour and 7 mm. in length. The posterior stigmatic plates, 

 situate on the hinder surface of the terminal or anal segment, are 

 large, very dark brown, nearly circular but with the adjacent inner 

 margins almost straight, and have each a circular central orifice. 

 On the ventral surface of the anal segment is "a dark yellow 

 chitinous plate showing six irregular paired tubercles " ; this plate 

 is surrounded by an area of rather coarsely granulated skin. 

 Pupation takes place in the ground beneath the dung, at a depth 

 of from half to three-quarters of an inch in the case of larvae in dung 

 lying on fine sand. The puparium, or pupa-case, is of the normal 

 Muscid type, dark brown in colour, barrel-shaped, and from 4 to 

 4.5 mm. in length, by 2 to 2.5 mm. in width. 



It is probable that Lyperosia does not often 



Lyperosia attack man, at any rate when it can get access 



and Disease, to domestic animals or big game, and it is not 



likely that flies belonging to this genus will prove 

 to be disease-carriers among human beings. With regard to 

 Lyperosia and animal trypanosomiases very little can yet be 

 said, and for Africa at any rate there is no experimental evidence 

 available. As has already been stated, Montgomery and Kinghorn 

 have recently expressed the opinion that in North- Western Rhodesia 

 at the present time trypanosomiasis is disseminated in herds of 



* Cf. Riley, C. V., and Howard, L. O., "The Horn-Fly (Hcematobia serrata, 

 Robineau-Desvoidy) " [= Lyperosia irritans, Linn.] : Insect Life, Vol. II., pp. 93- 

 103, Figs. 11-15(1889). 



M 



