August, 1944 



Ross: Caddis Flies of Illinois 



105 



Adults. — Length 13-15 mm. Color pat- 

 tern various shades of brown, fig. 393, the 

 pattern typical of many species of the sca- 

 laris group. Male with eyes of medium 

 size, each equal to about half the dorsal 

 area between them. Male genitalia, fig. 377: 

 tenth tergite somewhat hoodlike, the apex 

 almost truncate ; claspers with apical seg- 

 ment long, sinuate and pointed ; aedeagus 

 with stem straight and a dorsal continuation 

 of it extending over the apical portion; lat- 

 eral plates rounded at apex, the lateral 

 flange sharp and sinuate, mesal plates long 

 and curved ventrad, and the mesal cavity 

 about half closed. Female with ninth ter- 

 gite, fig. 386i1/, very similar to that of iii- 

 commoda. 



This species has been taken in abundance 

 at various points along most of the large 

 Illinois rivers; the records cover the entire 

 state. It occurs also in smaller streams, as 

 for example, in Quiver Creek near Havana, 

 where the larvae and pupae were taken in 

 large numbers from a small rapid. It is, 

 however, by no means as widespread along 

 the largest rivers as orris. The adults 

 emerge throughout the warmer months, 

 from April to late September. 



The range of the species, fig. 14, includes 

 most of the Corn Belt states with extensions 

 westward to Texas and eastern Colorado. 

 States for which we have records are Colo- 

 rado, Illinois, Indiana, Iowa, Kansas, Ken- 

 tucky, Minnesota, Missouri, Ohio, Okla- 

 homa, Tennessee and Wisconsin. 



Illinois Records. — Many males and fe- 

 males, taken April 15 to September 20, and 

 many larvae, taken May 5 to July 8, are 

 from Alton (Mississippi River), Deer 

 Grove (Green River), Freeport, Grafton, 

 Hardin (Illinois River), Havana (Quiver 

 Creek), Homer, Kankakee, Kappa (Mack- 

 inaw River), Lawrenceville, Momence 

 (Kankakee River), Mount Carmel (Wa- 

 bash River), Oakwood, Olney, Pontiac, 

 Quincy, Rockford, Rock Island, Rockton, 

 Savanna, Shawneetown, Spring Grove, Ster- 

 ling, Topeka (Quiver Creek), Urbana, 

 Wilmington. 



Hydropsyche valanis Ross 

 Hvdropsyche valanis Ross (1938^, p. 144); 



Larva. — Unknown. 



Adults. — Length 9-10 mm. Color tawny 

 with irregular flecking of light brown over 



the entire surface of the wings, forming a 

 slightly lighter mottling than that found in 

 simulans. Male with eyes large, each slight- 

 ly larger than dorsal width between them. 

 Male genitalia, fig. 378: tenth tergite short, 

 stubby, and incised on meson; claspers with 

 apical segment sinuate and rounded at apex; 

 aedeagus with stem slightly curved; apex 

 with lateral plates narrow from lateral 

 view, and mesal margin notched, the two 

 overlapping at apex; mesal cavity almost 

 completely open. Female with small eyes, 

 and color pattern slightly lighter than on 

 most of the species. Ninth tergite, fig. 

 386//, with very large clasper receptacle. 



Allotype, female. — Noblesville, Indiana: 

 Aug. 10, 1938, Ross & Burks. 



We have found this species at scattered 

 localities in northern Illinois, never in great 

 abundance. It has been taken along some 

 of the larger streams only, such as Indian 

 Creek and the Kankakee River. The dates 

 of capture indicate adult emergence from 

 May to late August. To date the larvae 

 have not been identified. 



Little is known about the range of the 

 species. Aside from the Illinois records, it 

 is known only from southern Minnesota 

 and central Indiana where again it was 

 found along fairly large rivers. 



Illinois Records. — Baker, Indian Creek: 

 May 12, 1938, Ross & Burks, \$. Kan- 

 kakee: July 21, 1935, Ross & Mohr, 1 $ ; 

 Kankakee River, May 17, 1937, Ross & 

 Burks, 3 $ ; May 6, 1938, Ross & Burks, 

 $ $ . Pontiac: Aug. 22, 1938, H. H. Ross, 

 $ $. Rock Island: June 23, 1928, Prison 

 & Hottes, 1 $ . Rockton: Rock River, July 

 2, 1931, Prison, Betten & Ross, $ $. 



Hydropsyche frisoni Ross 



Hydropsyche frisoni Ross (1938^, p. 142); 



Larva. — Fig. 354. Length 15 mm. Head 

 straw color with a dorsal brown area cover- 

 ing the frons and a few irregular areas 

 around it; thoracic sclerites and legs straw 

 color to brownish yellow. Frons flat, its 

 anterior margin straight. 



Adults. — Length 12-13 mm. Body dark 

 brown, similar in pattern to simulans, fig. 

 393. Male with eyes large, each equal to 

 dorsal area between them. Male genitalia, 

 fig. 379: tenth tergite short, almost truncate 

 at apex; apical segment of clasper somewhat 

 sinuate and pointed ; aedeagus with stem 



