EGGS OF HOUSE-FLY 75 



or casually, and it is by no means easy to distin- 

 guish and classify them. If the difficulty be 

 great as regards the insects themselves, it must 

 be greater as regards their eggs. 



It is well, therefore, to describe the two 

 principal representatives of the Diptera the 

 Muscidae and the Anthomyiidae. 



The Muscidae contains many of the most 

 abundant flies, including the common house-fly, 

 the blue-bottle or blow-fly, &c. 



The common house-fly (Musca domestica) 

 runs through its life-history in a very short 

 time. It lays about 150 eggs, that are very 

 small, on any kind of soft, damp animal or 

 vegetable matter. The larvae are hatched in a 

 day or two and feed on the surrounding carrion 

 or other putrid refuse ; they are fully grown in 

 five or six days, and then, passing through the 

 pupa stage, in another week or so emerge as 

 perfect flies. 



It is not to be wondered at that in favourable 

 localities they increase in a short time to such 

 enormous numbers. 



It is thought that flies pass the winter in 



