86 



Illinois Natural History Survey Bulletin 



Vol. 23, Art. 1 



streams. Records are available for Arkan- 

 sas, Georgia, Illinois, Indiana, Iowa, Kansas, 

 Kentucky, Michigan, Minnesota, Missouri, 

 Ohio, Oklahoma, South Dakota, Tennessee, 

 Texas and Wisconsin. 



Illinois Records. — Many males, females 

 and pupae, taken May 6 to October 10, 

 and many larvae, taken April 24 to Septem- 

 ber 11, are from Alton, Apple River Can- 

 yon State Park, Areola, Aurora, Bath, 

 Cairo, Carbondale, Charleston, Clinton, 

 Como (below mouth of Elkhorn Creek, 

 Rock River), Crystal Lake near Gulfport, 

 Danville (Middle Fork River), Dixon 

 (Rock River), DoAvns, Dundee, East Du- 

 buque, Effingham, Eichorn, Elgin (Botanical 

 Gardens, Fox River), Elizabethtown, Flor- 

 ence, Fox Lake, Freeport, Fulton, Galena 

 (Sinsinawa River), Gilman, Golconda, 

 Grafton (Mississippi River), Grand Tow- 

 er, Gulfport (Crystal Lake), Hamilton, 

 Hanover, Hardin (Illinois River), Harris- 

 nurg. Harvard, Havana, Henry, Herod, 

 Hillsdale, Homer, Horse Shoe Lake, Jer- 

 seyville, Kampsville, Kankakee (Kankakee 

 River), Kappa (Mackinaw River), Keiths- 

 burg, Lawrenceville, Le Roy, Massac Coun- 

 ty, Meredosia, Metropolis, Milan (Rock 

 River), Momence, Monticello, Morris, 

 Mount Carmel, Muncie, New Boston, New 

 Milford (Kishwaukee River), Oakwood 

 (Salt Fork River), Oregon (Castle Rock, 

 Rock River), Oswego, Ottawa, Pere Mar- 

 quette State Park, Pontiac, Putnam (Lake 

 Senachwine), Quincy (Burton Creek, Mis- 

 sissippi River), Richmond, Ripley (La 

 Moine River), Rockford, Rock Island, 

 Rockton, Rosiclare, Savanna (Mississippi 

 River), Serena (Indian Creek, Fox River), 

 Shawneetown, Shelbyville, South Beloit, 

 Springfield (Sangamon River), Sterling 

 (Rock River), Sugar Grove, Thebes, Ur- 

 bana, Valley City (Illinois River), Venedy 

 Station (Kaskaskia River), Wadsworth 

 (Des Plains River), Waukegan, Wilming- 

 ton, Yorkville, Zeigler, Zion. 



Hydropsyche Pictet 



Hydropsy che Pictet (1834, p. 199). Geno- 

 type, here designated: Hydropsyche cinerea 

 Pictet. 



In Illinois we have taken 18 species of 

 this genus, the various species living in prac- 

 tically every kind of permanent stream in the 

 state. Some are found abundantly in large 



rivers; others appear restricted to small 

 spring-fed brooks. 



The genus contains about 50 species, for 

 a large proportion of which females and 

 larvae have been identified. It is interesting 

 to note that in the scalaris group the larvae 

 can be identified with considerable ease, but 

 in the bifida group few characters have yet 

 been found by which to identify them. In 

 the females the opposite is true ; those of 

 the scalaris group present many small com- 

 plexes in which final specific identification 

 is extremely critical and unreliable, whereas 

 in the bifida group reliable specific charac- 

 ters are known for most of the species. 



Fine pioneer work outlining diagnostic 

 characters for the females of Hydropsyche 

 and Cheumatopsyche has been done by Den- 

 ning (1943). Denning has used the median 

 plate as a source of supplementary charac- 

 ters. Due to the difficulty of seeing this 

 plate in many species, its characters are not 

 used in the present keys, and for informa- 

 tion regarding them the student is referred 

 to Denning's work. 



Westwood (1840, p. 49) designated in- 

 stabilis Curtis as the genotype of Hydro- 

 psyche, but since this name was not included 

 in the original description of the genus, it 

 cannot function as the type species. H. 

 cinerea Pictet, an originally included species, 

 is here designated the genotype. Pictet's 

 species cinerea is considered a synonym of 

 instabilis. 



KEY TO SPECIES 



Larvae 



L Frons with two short, upturned, 

 stocky "horns" on anterior margin, 



fig. 346 orris, p. 106 



Frons without teeth on anterior mar- 

 gin 2 



2. Frons with anterior margin produced 



into a low, wide, angular portion, 



fig. 347 phalerata, p. 102 



Frons with anterior margin almost 

 straight 3 



3. Head entirely black or blackish brown, 



including extreme posterior portion, 

 excepting only a small area around 

 eye which is yellowish, fig. 348. . . . 



betteni, p. 99 



Head with at least red or yellowish 

 areas leading from eye to posterior 

 part of head or venter, fig. 352; usu- 

 ally with venter or back of head 

 yellowish, figs. 351, 355 4 



