§2 THE INSECT WORLD. 
several drops of red liquid in its trunk, and having tasted it, 
found it had the flavour which, from its appearance, he guessed 
it would have. 
The illustrious observer, who had already made all these dis- 
coveries on the formation and functions of the trunk of insects, 
often reflected on the fact that the liquors of which flies are most 
fond are enclosed under the skin of certain fruits, such as pears, 
plums, grapes, &c., or even under the skin of some animals of 
which they suck the blood. In order that the trunk of a fly may 
act under such circumstances, it is necessary for it to pierce and 
open the skin. If this is the case, flies ought to be possessed of 
a lancet. He looked a long time for this lancet, and at last found 
it. It is situated on the upper side of the part of the trunk 
which is terminated by the lips, and is placed in a fleshy groove, 
and enclosed in a case. It has a very fine point, and is of light 
colour (Fig. 61). The point is situated in the opening which is 
to be seen between the lips of the 
trunk, at its anterior end, through 
which the streams of liquid pass, on 
which the lips operate. That is the 
only opening of the lips; and the 
sucker which takes up the liquid is the 
same part which we just now called the case of the lancet. 
When once with Réaumur, one would never wish to leave him. 
However, we will stay these details, to continue our review of the 
principal kinds of Diptera. 
The genus Musca (fly), in which Linneus comprised the im- 
mense series of Diptera, with the exception of the T%pulide, the 
Tabanide, the Asilide, the Bombylide, and the Empide, is now 
reduced to the House Fly, and a few resembling it. The habits of 
these companions in our dwellings 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 parti- 

Yip 
Fig. 61.—Lancet of the Meat Fly. 
