106 



Illinois Natural History Survey Bulletin 



Vol. 23. Art. 1 



straight, constricted at base of apical por- 

 tion; apex of aedeagus angled dorsad, the 

 lateral plates rounded at apex, the lateral 

 flange considerably lower than mesal dome, 

 mesal cavity half closed, and mesal plates 

 short and somewhat triangular. Female 

 with small eyes, color pattern typical for 

 scalaris group. Ninth tergite as in fig. 3867. 



This species has been taken commonly but 

 not abundantly along the Middle Fork and 

 Salt Fork rivers near Oakwood ; aside from 

 this area we have only a single record, from 

 Indian Creek. The adult emergence con- 

 tinues from April to late August. 



Little is known regarding the range of 

 this species. Aside from Illinois, we have 

 only three scattered records from lower 

 Michigan. In this respect frisoni is remark- 

 ably similar to cheilonis, which has nearly 

 the same known range and has never been 

 found in Illinois outside the Oakwood area. 



Illinois Records. — Danville, Middle 

 Fork River: Aug. 27, 1936, Ross & Burks, 

 1 pupa, 2 larvae. Homer: July 11, 1927, 

 at light, Frison & Glasgow, 1 S . Muncie: 

 July 27, 1927, T. H. Frison, 2$. Oak- 

 wood, Salt Fork River: April 24, 1925, 

 T. H. Frison, 6^,1?; June 6, 1925, T. H. 

 Frison, 1 2 ; July 6, 1925, at light, Frison 

 & Glasgow, 5 S ; July 18, 1933, Ross & 

 Mohr, 2 S ; Aug. 25, 1936, H. H. Ross, 1 6 . 

 Serena, Indian Creek: June 16, 1939, B. 

 D. Burks, 1 S . 



Hydropsyche scalaris Hagen 



Hydropsyche scalaris Hagen (1861, p. 286); 

 cf,9. 



This species has not yet been taken in 

 Illinois but will almost certainly be found 

 with future collecting, since it has been col- 

 lected on practically all sides of the state, 

 with records from Georgia, Indiana, Mis- 

 souri, Oklahoma, Ontario and Wisconsin. 



The name scalaris is the one under which 

 many species have been confused. The selec- 

 tion of a lectotype by Banks (1936^, p. 127) 

 has given us a definite concept of this species 

 for the first time. 



Hydropsyche incommoda Hagen 



Hydropsyche incommoda Hagen (1861, p. 

 290); d'. 



Larva. — Unassociated with adult. 

 Adults. — Length 13-14 mm. Color 



brown with the typical mottled pattern sim- 

 ilar to that in fig. 393. Male with eyes of 

 moderate size, each subequal to one-half the 

 dorsal area between them. Male genitalia, 

 fig. 381, similar to simulans in shape of 

 tenth tergite and male claspers; aedeagus 

 with lateral plates long, lateral flange small, 

 parallel with dorsal outline of stem, mesal 

 cavity almost entirely open, and mesal plates 

 large and projecting ventrad. Female with 

 ninth tergite as in fig. 386Ai^. 



Allotype, female. — Tavares, Lake Coun- 

 ty, Florida: March 23, 1936, F. N. Young. 



The species treated under the name in- 

 commoda by Betten (1934, p. 188) is not 

 the true incommoda, but is betteni (see p. 

 99). 



We have taken this species at several 

 localities in the eastern, central and south- 

 ern parts of Illinois, usually in small num- 

 bers, and never in a heavy flight. The col- 

 lections are associated w^ith medium-sized 

 to large streams. The adults emerge over 

 a long period, our records being scattered 

 from April 24 to August 27. 



In addition to Illinois, the species is known 

 only from Florida, Georgia and North Car- 

 olina; presumably it occurs in suitable situ- 

 ations in the intervening area between these 

 southeastern states and Illinois. 



Illinois Records. — Carmi, Little Wa- 

 bash River: April 24, 1935, T. H. Frison, 

 \$. Kappa, Mackinaw River: Sept. 14, 

 1937, Ross & Burks, 4 <5 . Mahomet: Aug. 

 3, 1937, Ross & Burks, $ $ , $ 9 . Mo- 

 mence: Aug. 16, 1938, Ross & Burks, 1 $ ; 

 Kankakee River, May 29, 1939, Frison & 

 Ross, \i. MoNTicELLo: May 7, 1936, 

 Ross & Burks, \$. Oakwood: Sept. 20, 

 1935, DeLong & Ross, 1 $ ; Salt Fork River, 

 July 31, 1939, Burks & Riegel, \$. PoN- 

 tiac: Aug. 22, 1938, H. H. Ross, 5^. 

 Shawneetown: May 27, 1928, at light, 

 T. H. Frison, 1 $ . Venedy Station, Kas- 

 kaskia River: Aug. 27, 1940, Mohr & 

 Riegel, 9 ,? , 9 9 . 



Hydropsyche orris Ross 



Hydropsyche cornuta Ross (1938^, p. 141); 

 d^, 9. Preoccupied. 



Hydropsyche orris Ross (1938^, p. 121). 

 New name. 



Larva. — Fig. 346. Length 14 mm. Head 

 brown with pale areas on lateral and pos- 

 terior portions and frons; "thoracic sclerites 

 and legs straw colored to brownish yellow. 



