104 



Illinois Natural History Survey Bulletin 



Vol. 23, Art. 1 



Ross & Burks, 4 5,5$; June 15, 1938, D. 

 T. Ries, 5$; June 17, 1938, Frison & 

 Mohr, 4 5 ; June 18, 1938, Ries & Werner, 

 6$ ; June 22, 1938, D. T. Ries, 6$ ; June 

 27, 1938, F. Werner, 1 5 , 1 $ ; June 5, 1941, 

 Floyd Werner, \$, 15; July 11, 1941, D. 

 T. Ries, 1 $ . Sugar Grove: June 13, 1939, 

 Frison & Ross, 1 $ . 



Hydropsyche arinale Ross 



Hydropsyche arinale Ross (1938«, p. 143); 



Larva. — Fig. 351. Length 15 mm. Head 

 mostly brown with yellowish markings 

 around and under the eyes, on the ventral 

 surface and the postero-lateral angles. Tho- 

 racic sclerites and legs brownish yellow. 

 Frons flat, its anterior margin straight. 

 Setae on the dorsum of the abdomen rela- 

 tively sparse. 



Adults. — Length 9-10 mm. Color vari- 

 ous shades of brown similar to the typical 

 pattern for the scalaris group, as in fig. 393. 

 Male with eyes of medium size, each equal 

 to at least two-thirds of the dorsal area 

 between them. Male genitalia, fig. 376, with 

 tenth tergite somewhat hood shaped and 

 declivous; claspers with apical segment sinu- 

 ate and pointed; aedeagus with stem con- 

 stricted near middle, appearing somewhat 

 moniliform from ventral view, the lateral 

 processes wide and the mesal cavity almost 

 entirely open. Female similar in color and 

 general structure to other members of the 

 scalaris group. Ninth tergite as in fig. 386£. 



Allotype, female. — Serena, Illinois, along 

 Indian Creek: May 12, 1938, Ross & 

 Burks. 



We have taken this species at various 

 points in the northern half of the state. It 

 shows a preference for such streams as 

 Indian Creek, which is relatively clear and 

 provided with many riffles or rapids. Our 

 only large collections of adults were taken 

 early in May, but emergence continues 

 through August. 



The range of the species seems to follow 

 rather closely the outer fringe of the oak- 

 hickory forest. We have records from Ar- 

 kansas, Kansas, Missouri, Oklahoma and 

 Wisconsin; these all indicate the same type 

 of stream preference as do our Illinois 

 records and increase the seasonal emergence 

 of adults from April to September. 



Illinois Records. — Many males and fe- 

 males and two pupae, taken May 12 to 



September 5, and many larvae, taken May 

 12 to May 16, are from Algonquin, Aurora, 

 Baker, Des Plaines (Fox River), Oregon, 

 Pontiac, Quincy (stream near Cave Spring), 

 Richmond, Serena (Indian Creek), Starved 

 Rock. 



Hydropsyche simulans Ross 



Hydropsyche simulans Ross (1938a, p. 139); 

 c?", 9. 



Larva. — Fig. 352. Length 18 mm. Head 

 dark brown with irregular light areas on 

 the sides, posterior portion and venter; pro- 

 notum brown, remainder of thoracic scle- 

 rites and legs straw color to brownish yel- 

 low. Frons flat, its apical margin straight. 

 Dorsum of abdominal segments with flat- 

 tened setae relatively abundant. 



Fig. 393. — Hydropsyche simulans, cf . 



