DIPTERA. 83 



ticularly on mushrooms 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 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 trans- 

 parent yellow at the sides, in the males ; and is 

 speckled with black. The feet are black ; the 

 wings transparent, and yellowish at the base. F i g . 62.- House Fi y (,i/,/.<m 

 This species is extremely plentiful through- 

 out 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 (Musca 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, 

 with a slight ash-coloured down. Its forehead is silvery at the 

 front and sides, the abdomen is edged with black, the wings hyaline 

 and yellow at the base. 



Section of the Anthomysida. The section of Anthomysidtz com- 

 prises insects which appear to be Creophili whose organisation has 

 become weakened by almost insensible degrees. Their colours vary 

 very much black, grey, and iron- colour are everlastingly shaded 

 and blended together. To that may be added reflections which 

 are above the ground colour, and which change the hues of the 

 little animal according to the incidence of the rays of light. The 

 Anthomysidce resemble the genus Musca very closely in their habits 

 as well as in their organisation. 



In this group of Diptera we will first say a few words about the 

 Anthomyas. These flies are to be found in all places and on all 

 flowers, particularly on the heads of composite and nmbelliferco. 



G 2 



