82 THE INSECT WOELD. 



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 oi 

 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 pos- 

 sessed of a lancet. ' He looked a long time for this lancet, and at 

 last found it. It is situated at the top 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 Heaumur, 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 Linna3us comprised the immense 

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

 the Asilici, the Bombyliarii, and the Empidice, 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 par- 



