109 



powerful blows with tlieir mandibles (small mouth hooks) which 

 pierce through the outer skiu of the larva of M. doinestica and 

 the latter, soon ceasing to resist, succumbs. The author never 

 observed that a larva of 31. stahulans which had actually killed 

 a larva of M. domestica devoured its victim alone ; usually a 

 number of other individuals joined in the consumption of the 

 dead larva. The author also never observed the larvae of 

 M. stahulans eating each other, as is the case with some other 

 larvae (Pohjetes alholineata). In some of his experiments the 

 larvae of M. stahulans were fed with larvae of other flies, such 

 as Musca ovipara or M. cornicina, taken from the dung of cattle. 

 Although the latter larvae were generally fully grown, those of 

 Muscina stahulans immediately attacked and quickly devoured 

 them. On this live diet the larvae grew A^ery quickly, and when 

 fully developed, refused further live prey. Besides the living 

 larvae of ilies the author used fresh dead flies or other insects as 

 food and found that the larvae bored into their bodies and ate the 

 contents. 



The experiments of the author with the larvae of M. stahulans 

 ajid of Hydrotaea dentipes proved that the former also destroyed 

 the larvae of the latter fly which, as is already known, are also 

 carnivorous and destroy the larvae of M. domestica. In the 

 opinion of the author the harm done by M. stahulans in destroy- 

 ing the larvae of a useful fly such as H. dentipes outweighs its 

 utility as a destroyer of the larvae of the house-fly. There are, 

 however, other species of flies, wdiich destroy the larvae of 

 JI. stahulans. The larvae of Polyetes alholineata in horse-dung 

 are, the author says, always victorious over those of M. stahulans, 

 even when the latter are the larger, and he claims to have proved 

 this by experiments. It is known that another species of Muscina, 

 M. pahuloruvi, is a serious enemy of the larvae of Sciara nnilitaris. 



The larvae of M. stahulans have been found not only in human 

 faeces and in the dung of cattle and horses, but also on raw and 

 cooked meat, on carcases of different vertebrates (mammals, birds 

 and amphibians) and invertebrates (insects, their larvae and 

 pupae), in rotten bulbs and vegetables, on fungi, in old 

 cheese, &c. 



The author mentions statements of Goureau, Aube and Laboul- 

 bene, who found on trufiles large colonies of larvae of M. stahulans , 

 instead of the larvae of the usual flies, Helomyza gigantea {tuheri- 

 Tora), H. lineata and H. ustulata, which live on these fungi; 

 evidently the rotting truffles attracted the M. stahulans, the larvae 

 of which had exterminated the former inhabitants. 



The ability of M. stahulans to penetrate into all sorts of dark 

 and closed spaces and rooms in which human food is preserved, 

 and to infect this food with different pathogenic organisms, may 

 lead to very serious consequences. Apart from various diseases 

 which may be spread in this way, food on which the fly's eggs are 

 laid, when consumed by human beings or other animals, especially 

 in the case of individuals suffering from chronic disorders of the 

 bowels, may bring about very grave and painful complications. 

 For some unknown reason, the larvae of flies which in nature 

 usually pass quickly through all their different stages, are in 

 many cases able to remain in the human intestine in the larval 



