FLIES. 235 



a house-fly, and the abdomen is marked with several yellow 

 stripes. The bite is harmless to man and to wild animals, being 

 scarcely more severe than that of a mosquito, but a very few bites 

 are sufficient to kill an ox, horse, or dog ; not immediately, but 

 by inducing a peculiar and incurable disease within a very few 

 days. Although some still dispute the assertion that the fly is the 

 real cause of the death of cattle, yet the natives of the regions in 

 which it is found, and nearly all travellers, are unanimous on the 

 subject. Packard (writing in America) appears to have strangely 

 misunderstood the accounts of this fly, for he speaks of its killing 

 animals by its painful bite ; whereas it is the poisonous nature of 

 the bite which produces death, if African travellers are correct. 



Mesembrina Meridiana, Linn., is a very conspicuous black fly 

 with the base of the wings bright yellow. It measures about half 

 an inch in length. The larva live in dunghills, on which the flies 

 will sometimes settle ; at other times they may be seen swarming 

 round the trunk of a tree, and settling occasionally. They delight 

 in broad daylight, and are seldom or never seen in houses. 



Several blue and green flies belonging to the genera Calliphora 

 and Lucilia, Desv., are produced from larvae which feed on more 

 or less putrid flesh. Such are the Blow-Fly or Blue-bottle (Calli- 

 phora Vomitoria, Linn., which frequently comes into our rooms in 

 summer ; and the smaller Green-bottle Fly (Lucilia Ccesar, Linn.), 

 a brilliant golden-green fly, about the size of a common house-fly, 

 which is often common about hedges, settling on the leaves. A 

 French species resembling this (L. Bufonivora, Mincer.) is parasitic 

 on toads, which its larvae attack in the head, like those of the 

 genus Sarcophila. 



Musca Domestica, Linn., our common house-fly, is grey, with 

 the abdomen more or less yellowish in the male, and darker in the 

 female. It is very common in houses, especially in summer and 

 autumn. The larvae live in dunghills. Our house-flies have many 

 enemies. They may often be observed with a small animal re- 

 sembling a scorpion without the sting clinging to one of their legs. 

 This is a species of the genus Chelifer, and is one of the Arachnida ; 

 but it is not certainly known whether it causes any injury to the 

 fly, or whether it simply avails itself of the fly's wings to convey 

 itself from place to place. It is very common, too, to find flies 

 fixed to the glass of a window with a whitish film around them : 

 this is a parasitic fungus (Empusa Muscarum) which has germinated 

 in the body of the fly, and has finally caused its death. 



