DIPTERA. 83 



The genus Miisca (fly), in which Linnaeus comprised the immense 

 series of Diptera, with the exception of the Tipnlidce, the Tabanidce, 

 the Asilidce, the Bombylida, and the Empidce, is now reduced to the 

 House Fly and a few resembling it. The habits of these trouble- 

 some companions are in conformity with the two great principles of 

 animal life, that is, eating and propagating their species. 



Flies feed principally on fluids which exude from the bodies of 

 animals ; that is, sweat, saliva, and other secretions. They also seek 

 vegetable juices ; and they may be seen in our houses to feed eagerly 

 on fruits and sweet substances. 



The common flies deposit their eggs on vegetables, and particu- 

 larly on fungi in a state of decomposition, on dung-heaps, cow dung, 

 &c. They are essentially parasites, settling on both man and beast, 

 to suck up the fluid substances which are diffused over the surface of 

 their bodies. In our dwellings they eat anything that will serve to 



Fig. 61. Lancet of the Meat Fly. Fig. 62. -House Fly (Muscn. domestica). 



nourish them. Generation succeeds generation with the greatest 

 rapidity. 



The House Fly (Musca domestica, Fig. 62) is about three lines in 

 length, ash coloured, with the face black, the sides of the head 

 yellow, and the forehead yellow with black stripes ; the thorax is 

 marked with black lines; the abdomen is pale underneath, and a 

 transparent yellow at the sides, in the males, and is speckled with 

 black. The feet are black ; the wings transparent, and yellowish at 

 the base. This species is extremely plentiful throughout the whole 

 of Europe. Every one knows how annoying it is towards the end of 

 the summer, and especially so in the South of France during the hot 

 season. 



The Ox Fly (MusctL bovina), a near relation of the house fly, is 

 also very common. It settles on the nostrils, the eyes, and the 

 wounds of animals. 



The Executioner Fly (Musca carnifex), which is not rare in 

 France, also attacks oxen. It is of a dark metallic green colour 



G 2 



