Feb. 



European Frit Fly in North America 



457 



Fig. 6. — Oscinis frit: Female abdomen, distended ■with eggs and ovi- 

 positor protruded. (From alcoholic specimen, highly magnified.) 



Legs of ordinary structure; coxae and femora black, the trochanters and knees often 

 yellowish; tibiae rarely entirely black, usually paler at base and tip, the fore and 

 middle tibiae often wholly yellow, hind ones, however, always with at least a black 

 ring. Tarsi yellow, darkened toward tips. 



Wings subhyaline, sometimes a little brownish, varying moderately in width; costa 

 extending to fourth vein; the costal segment between the tips of the first and second 

 veins about i}^ times as 

 long as the following one; 

 fourth vein ending very 

 slightly behind the apex; 

 anal angle well developed. 



MALE GENITALIA 



Since these organs in 

 many insects throw a 

 great deal of light on 

 the limits of species, 

 the genitalia of about 

 25 males were mounted for study after being boiled for from 5 to 10 

 minutes in 10 per cent caustic potash; among these were 5 specimens 

 of the oat fly from Garforth, England, kindly furnished by Prof. T. H. 

 Taylor, of Leeds University; others were from Missoula, Mont., Sioux 

 City, Iowa, and La Fayette, Ind. No appreciable difference was found 

 in any of these. The general features are shown in figure 7, drawn 

 from a specimen taken at Missoula, Mont. 



The fifth abdominal segment in the male is very small and normally 



retracted so as to be invisible. The sixth 

 segment is also small, rather cup-shaped, 

 open behind and below, and at least its 

 posterior part is visible in life. It bears a 

 symmetrical pair of long claspers below, 

 curving backward and toward the middle 

 line. The anus is situated at the middle of 

 the segment behind; and on each side of 

 this is a protruding, strongly chitinized 

 lobe, which is produced forward inside both 

 above and below ; the upper arm keeps close 

 to the side of the cavity and joins the pro- 

 duced upper margin of a curved plate with 

 a thickened edge, which extends forward so 

 as to form a trough, almost a tube, through the open anterior end of 

 which the penis projects. This organ arises in the ventral part of the 

 sixth segment in the median line and is supported in part from the 

 ventral forward extension of the lobe beside the anus. 



Fig. 7.- 



-Oscinis frit: Male genitalia, 

 highly magnified. 



