no 



DIPTERA OF MINNESOTA. 



very elongated, being .023 of an inch long and .005 of an inch broad. 



"The larva or maggot is very pale green and very slender, being about 

 one-quarter of an inch long by one-thirty-second of an inch wide. Its head 

 is provided with a pair of black toothed hooks. The covering of the apparent 

 pupa is simply the shrunken larval skin, which protects the true pupa forming 

 inside. As soon as the real pupa is formed it becomes visible through the 

 transparent larval skin, and is seen to be also of a pale green color. It is about 

 one-sixth of an inch long and about one-thirteenth of an inch broad. As 

 the imago is formed inside the pupa, the eyes, wing-pads and legs become 

 apparent. 



"A careful comparison has convinced me that the insects bred from Min- 

 nesota wheat straw are identical with those bred from eastern and southern 

 straws, and that the flies vary among themselves to a sufficient extent to ac- 

 count for extreme differences that may occur." 



The reader must not suppose that these are the only flies found 

 in this family, nor that all the flies occuring therein are wheat pests. 

 Such is by no means the case. Aldrich in 1904 lists about 135 species 

 of Oscinids in North America, the locality froin which specimens were 

 secured indicating a wide range over this country. 



They are all small flies and quite common. A locally abundant 

 fly of this family, Oscinis paUipes, Loew., commonly known as "The 



Fig. 101. Oscinis f'allipes, Bloodsucking Oscinis. Lugger. 



Blood-sucking Oscinis," is curious, in that it so markedly departs, 

 in its adult stage, at least, from the habits of its vegetarian congeners 

 as well as its other family relatives. It is very small, black, with 

 yellow face and legs (see Fig. 104,) where the line below the insect 

 shows the exact size of the fly, and its expanded wings. This fly in 



