August, 1944 



Ross: Caddis Flies of Illinois 



267 



wings suffused with varying shades of Plains. Records are available for Arkansas, 



brown. ^Vlale genitalia, fig. 961, p. 288, with California, Colorado, Florida, Georgia, Illi- 



hand-shaped claspers, narrow and beaklike nois, Indiana, Kentucky, Michigan, Minne- 



tenth tergite and cylindrical, curved aedea- sota, Missouri, Montana, New Brunswick, 



gus. An added diagnostic character is the New Hampshire, New York, Nova Scotia! 



-.II,,,,,,'--:- -.- -';;,in ./ 



-.Bijiilliii"'- ■■""'»i||„',iii; 



Fig. 905. — Helicopsyche 

 borealis, larva. 



slightly clavate, sclerotized spur of the sixth 

 sternite. Female abdomen with very distinc- 

 tive pattern of sclerites, those of the basal 

 segments reticulate, as in fig. 907; bursa 

 copulatrix small and stalked. The male 

 abdomen has similar reticulation. 



This species is widely distributed in Illi- 

 nois but is confined to relatively clear and 

 swift streams, such as the Kankakee and 

 Salt Fork Rivers and Split Rock Brook, 

 and is found also in the glacial lakes of the 

 northeastern corner of the state. The lar- 

 vae are found chiefly under stones. There 

 is apparently a continuous succession of 

 generations, our adult emergence ranging 

 from May 28 to September 7. 



This insect is one of the best known caddis 

 flies and has received much attention. Vor- 

 hies (1909) has reared and described all 

 stages very completely. 



Betten (1934) also has illustrated char- 

 acters of this species in considerable detail. 



The curious snail-like case has attracted 

 the attention of many entomologists and col- 

 lectors of natural history objects. It is re- 

 markably constant in structure, varying little 

 in shape over the species range. 



The continental range of the species is 

 very wide, stretching from Mexico north- 

 eastward to Nova Scotia and westward to 

 Montana and Oregon; the range embraces 

 most of the forested areas of the continent, 

 forming a complete circle around the Great 



Fig. 906. — Helicopsyche borenlis, case. 



Ohio, Oklahoma, Ontario, Oregon, Penn- 

 sylvania, Saskatchewan, South Dakota, 

 Texas, Virginia, West Virginia, Wisconsin 

 and Wyoming. 



Illinois Records. — Many males, females 

 and pupae, taken May 14 to September 7, 

 and many larvae, taken February 1 to Octo- 

 ber 30, are from Antioch, Apple River Can- 

 yon State Park, Baker (Indian Creek), 

 Cedar Lake, Channel Lake, Chemung 

 (Piscasaw Creek), Fox Lake, Herod (east 

 fork of Grand Pierre Creek), Homer, Kan- 

 kakee (Kankakee River), Leland, Martha 

 Iron Furnace (Hog Thief 

 Creek), McHenry, Mo- 

 mence (Kankakee River), 

 Muncie (Stony Creek), 

 Oakwood (Salt Fork 

 River), Richmond, Rock 

 Island, Serena (Indian 

 Creek), Spring Grove, 

 Sterling, Urbana (Salt 

 Fork River), Utica (Split 

 Rock Brook), Wilming- 

 ton (Kankakee River). 



Fig. ^^1. — Helicopsyche 

 borealis, female abdomen, 

 ventral aspect. 



