CHAPTER XVII 



THE BLOW-FLIES, CALLIPITORA ERYTHROCEPHALA MEIG. 

 AND C. VOMITORIA L., AND THE SHEEP MAGGOT OR 

 "GREEN BOTTLE" FLY, LUC I LI A CAESAR L. 



The large blow-fly or "blue bottle," C. enjthrocephala , is a 

 widely divStributed and common species in Europe and North 

 America. In the past, but less commonly now, the name of the 

 other species, C. vomitoria, has been indiscriminately applied to 

 both species. C vomitoria is, however, much less common than 

 C erythrocephala. They can be distinguished by the fact that in 

 the latter species the genae are fulvous to golden yellow and are 

 beset with black hairs, whereas in G. vomitoria the genae are 

 black and the hairs are golden red. 



Calliphora eri/throcephala has been described in detail by 

 Lowne (1870, 1895). Its appearance, with its bluish-black thorax 

 and dark metallic blue abdomen, is sufficiently well known as to 

 render a description of the adult flies unnecessary. Its length 

 varies from 7 to 13 mm. The larvae are necrophagous, and the 

 flies deposit their eggs on any fresh, decaying or cooked meat, and 

 also upon dead insects ; Howard (1909) has found the fly on fresh 

 human faeces. On one occasion, when obtaining fresh food material 

 in the form of wild rabbits upon which to rear the larvae of C. 

 erythrocephala, I found the broken leg of a live rabbit, which had 

 been caught in a spring trap set the previous evening, a living 

 mass of small larvae, which were devouring the animal while it 

 was still alive. An enormous number of eggs are laid by a single 

 insect; Portchinsky (Osten Sacken, 1887) found from 450 to 600 

 eggs, though I have not found so many. Fabre, in his Souvenirs 

 entomologiques, records G. vomitoria depositing 300 eggs in one 

 batch and more were subsequently deposited, and he believed, on 

 the evidence which he secured, that as many as 900 may be 



