100 



DIPTERA OF MINNESOTA. 

 OSCINIDAE, 



Minnesota has occasion to know these flies, for in the family are 

 two wheat pests, which at times make their presence unpleasantly 

 known within the confines of our state, and which have long been injur- 

 ious to wheat, rye and barley in Europe. I refer to the Frit Fly, 



l-'ig. 102. Flit I'ly, Oxciiiis xoror, imago, larva and pupaiium. Lugger. 



Oscinis snror, ■\Iacq.. Fig. 102, and the Wheat Stem Maggot, 2\Icroiny::a 

 americaiia, Fitch, Fig. 103. The first of these, well shown in the 

 illustration, and quite troublesome here in 1892, prevents the filling 

 of the heads, and by working in the stem in the maggot stage so 

 weakens it as to allow it to bend, thus bringing the heads upon or near 

 the ground. This injury is first seen about the time the head begins to 

 form. The part of the stem above the first or second joint generally 

 wilts at that time, if afifected, and bends over. Minute worms may 

 be found in the early stage of the trouble, causing this weakening by 

 their presence in the straw just above a joint. These are the larvae 

 of the Frit Fly, and are shown in the illustration at (b). If, however, 

 the examination of these stems be delayed until late, one finds not the 

 larva, but the puparium (c), which is the hardened and browned 

 skin of the larva, and contains the pupa or larva (October). Some- 

 times three or more of these puparia are found together. They are 



