The genus Musca (fly), in which Linnæus comprised the immense series of Diptera, with the exception of the Tipulidæ, the Tabanidæ, the Asilidæ, the Bombylidæ, and the Empidæ, is now reduced to the House Fly and a few resembling it. The habits of these troublesome 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.
| Fig. 61.—Lancet of the Meat Fly. | Fig. 62.—House Fly (Musca domestica). |
The common flies deposit their eggs on vegetables, and particularly 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 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 (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 Anthomyides.—The section of Anthomyides comprises 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 Anthomyides resemble the genus Musca very closely in their habits as well as in their organisation.
