August, 1944 



Ross: Caddis Flies of Illinois 



241 



Creek: May 12, 1938, Ross & Burks, 7 

 larvae; May 17, 1938, Ross & Burks, 2i, 

 2$, 1 larva (all reared in cage at Spring 

 Grove, Illinois) ; May 27. 1938. Ross & 

 Burks, 1 larva; June 16, 1939, B. D. Burks, 

 1?. 



Oecetis scala Milne 



Oecetis scala Milne (1934, p. 17); d". 



Not yet taken in Illinois, but apparently 

 with a widespread though scattered range, 

 so that the species may be looked for in 

 the state with future collecting. To date 

 it has always been collected in small num- 

 bers, with records available from Maryland. 

 New Jersey, North Carolina and Pennsyl- 

 vania. 



Oecetis osteni Milne 



Oecetis osteni Milne (1934, p. 17); d^, 9. 



Larva. — Unknown. 



Adults. — Length 9 mm. Color various 

 shades of brown without conspicuous mark- 

 ings. Male genitalia, fig. 819: tenth tergite 

 composed of a pair of fairly long, sclerotized 

 arms, wide at base, tapering to a curved 

 apical beak; aedeagus narrow and arcuate, 

 in repose fitting into the V of the beak of 

 the tenth tergite; claspers with the basal 

 portion somewhat rectangular, tapering to 

 a short, apical point. Female genitalia, 

 fig. 826, readily identified by the dark area 

 on the eighth sternite and the simple bursa 

 copulatrix. 



In Illinois this species is restricted to the 

 extreme northern portion of the state and 

 has been taken most commonly around the 

 glacial lakes in the northeastern corner. 

 The adults have been taken from late June 

 to the latter part of August. In other states 

 the records are most frequently associated 

 with lakes, but the species undoubtedly 

 occurs also in rivers. 



The range of the species includes a band 

 through the Northeast from Minnesota 

 eastward to New Brunswick. Records are 

 available from Illinois, Massachusetts, 

 Michigan, Minnesota, New Brunswick, 

 New Hampshire, New Jersey, New York, 

 Ontario. Quebec, Virginia and Wisconsin. 



Illinois Records. — Antioch: July 7, 

 1932, at light, Prison & Metcalf, M , 1 $. 

 Fox Lake: June 30, 1935, DeLong & Ross, 



$ $, 9 5 ; June 10, 1936, Ross & Burks, 

 1$. Fulton: July 20, 1927, Frison & 

 Glasgow, 1 $ . Grass Lake: July 14, 1926, 

 Frison & Hayes, 1$. Grayslake: Aug, 

 20, 1939, Mohr & Riegel, \$. Richmond: 

 June 25, 1938, Burks & Boesel, 1 $ . Spring 

 Grove: Aug. 12, 1937, at light, Ross & 

 Burks, 1 $ . 



Oecetis immohilis (Hagen) 

 Setodes immobilis Hagen (1861, p. 283); d". 



Larva. — Unknown. 



Adults. — Length 9 mm. Color various 

 shades of brown without conspicuous mark- 

 ings. Male genitalia, fig. 823: tenth tergite 

 composed of a single semimembranous, fair- 

 ly short process; cerci ovate; claspers fairly 

 short, the dorsal margin sinuate, the apical 

 process fairly short and the basal portion 

 appressed for a considerable distance on 

 meson; aedeagus stout at base, the apex 

 forming a definite beak. Female genitalia, 

 fig. 830, with ninth sternite diamond shaped, 

 the posterior sides of the diamond raised 

 and fencelike, bursa copulatrix almost circu- 

 lar. 



In Illinois we have taken this species 

 only in the extreme northern portion and, 

 as with osteni, it has been taken abundantly 

 only around the glacial lakes of the north- 

 east corner of the state. All our records 

 for Illinois are in late May, June and early 

 July; records for other states, however, in- 

 dicate an emergence which continues into 

 August and September. 



The range of the species includes most 

 of the Northeast; records are from Illinois, 

 Indiana, Michigan, New Brunswick, New 

 York, Nova Scotia, Ohio, Ontario, Sas- 

 katchewan and Wisconsin. 



Illinois Records. — Fox Lake: July 1, 

 1931, Frison, Betten & Ross, $ $, 9 ? ; 

 June 30, 1935, DeLong & Ross, $ $, $ 9 ; 

 May 28, 1936. H. H. Ross, $ $ ,\$ pupa; 

 June 10, 1936, Ross & Burks, 9$. Johns- 

 burg, Fox River: May 28, 1936, H. H. 

 Ross, 2$, 29. Pistakee Lake: June 12, 

 1936, H. H. Ross, \$. Rock City: May 

 24, 1938, Ross & Burks, 1 $ . Spring 

 Grove: June 9, 1938, Mohr & Burks, 1 $. 



Oecetis cinerascens (Hagen) 



Setodes cinerascens Hagen (1861, p. 282); d^. 

 Oecetina fumosa Banks (1899, p. 216); 9. 



