Feb. 2, 1920 European Frit Fly in North America 453 



This study has led to the conclusion that Oscinis pusilla, O. nitidissima, 

 O. carhoruiria, O. variabilis, O. nigra Tucker, and O. sorer Macquart 

 are all synonyms of O. frit. The multiplicity of names has arisen from 

 the variability and wide distribution of the species. The long-continued 

 confusion has existed mainly because the taxonomists since Linnaeus 

 who have classified the adults have paid little or no attention to the habits, 

 while the biological workers have been uninformed as to the characters 

 used in classification and have applied whatever name was given them. 



Typical Musca frit as defined by. Linnaeus has the femora and tibiae 

 wholly black; Oscinis nigra Tucker is precisely this, as described from 

 Denver, Colo. This extreme form apparently does not occur east of 

 the Rocky Mountain region but is common westward. O. frit as 

 recognized by Becker, however, includes eastern and western forms 

 with a small amount of yellow on the tibiae, at base and tip. When 

 the yellow portions are more extensive, so that the front and middle 

 tibise are merely ringed with black, the form O. pusilla is reached, of 

 which O. carhonaria is an exact synonym. From this form O. varia 

 bilis differs only in having a more shining thorax and is the same as 

 O. nitidissima of Europe, North American specimens having been so 

 identified by Becker. All gradations from the somewhat shining dorsal 

 surface of O. frit to the highly shining one of O. nitidissima can be readily 

 found. -Coquillett separated some specimens with shorter frontal tri- 

 angle as O. soror of Macquart, but this is also a variable character; 

 moreover, Macquart in describing it said nothing about the species 

 having a short triangle. 



NATURE OF INJURY 



In the commonest form of injury minute maggots occur in young 

 stems of wheat close to the ground. They are easily distinguished from 

 the larvse of the Hessian fly (PhytopJiaga destructor Say) from the fact that 

 the larva is in the center of the stem and crawls actively when removed, 

 whereas the Hessian-fly larva is between the bases of the leaves and is 

 extremely inactive. The Oscinis frit larva often causes the central leaf 

 to die and turn brown, those about it remaining green; this the Hessian 

 fly larva never does. 



DISTRIBUTION IN NORTH AMERICA 



The region of greatest abundance of the frit fly in North America cor- 

 responds rather closely with that in which winter wheat is grown, from 

 the Great Lakes to the Ohio River, and westward about as far as the 

 Missouri. But outside this area it is often common locally from the 

 Atlantic to the Pacific and from Ottawa, Canada, to the Gulf of Mexico. 

 The fly occurs generally wherever grass is abundant and remains green 

 for a considerable part of the year. So in the arid West it occurs in spots, 

 along streams or in irrigated pastures, or in the higher altitudes where 



