100 



Illinois Natural History Survey Bulletin 



Vol. 23, Art. 1 



rounding eye; legs yellow to yellowish 

 brown. Frons small, fiat, the anterior mar- 

 gin straight. Dorsum of abdomen with con- 

 spicuously flattened hairs scattered among 

 the simple appressed ones. 



Adults. — Length 12-13 mm. Various 

 shades of brown, antennae with first seven 

 segments of flagellum having a dorsal black 

 V-mark; wings reticulate with various 

 shades of brown, resembling closely the pat- 

 tern of bifida. Male genitalia, fig. 368, with 

 tenth tergite somewhat hood shaped; clasp- 

 ers with apical segment long and tapering; 

 and aedeagus long, curled at base, with stem 

 straight and apex almost truncate. Female 

 similar to male in size, color and structure. 

 Eighth tergite with a long brush on apico- 

 ventral corner and with lobes of eighth ster- 

 nite somewhat produced at apex. Ninth ter- 

 gite with large clasper receptacle, fig. 385. 



This species was treated as incommoda 

 by Betten (1934, p. 188). It frequents a 

 variety of small streams throughout the 

 northern two-thirds of Illinois. It has been 

 taken in abundance many times, both in 

 Illinois and elsewhere, in the shallow, swift 

 film of water running over the spillways of 

 small dams. Otherwise its favorite haunt 

 seems to be the riffles of small to medium- 

 sized streams. The adults emerge from 

 April to September. 



The species' range seems to include a 

 sort of crescentic area through much of 

 the Northeast and continuing south through 

 the Appalachians. We have records from 

 Georgia, Illinois, Indiana, Michigan, New 

 York, Ohio, Ontario and Wisconsin. 



Illinois Records. — Many males, females 

 and pupae, taken April 11 to August 23, 

 and many larvae, taken March 2 to August 

 13, are from Apple River Canyon State 

 Park, Clinton (Weldon Springs), Elgin 

 (Botanical Gardens, Rainbow Springs), Ga- 

 lena, Gibson City, Havana (Quiver Creek), 

 Marengo (Coon Creek), Matanzas Lake, 

 McHenry, Milan, Momence, Mount Car- 

 roll, Oregon, Richmond, Rock City, St. 

 Anne, Utica, Watson, White Pines Forest 

 State Park. 



Hydropsyche depravata Hagen 



Hydropsyche depravata Hagen (1861, p. 290); 

 9. 



This species is southern in distribution, 

 roughly occupying the area south of the 



range of betteni. It has not yet been taken 

 in Illinois, but from both Kentucky and 

 Indiana we have records which are very 

 close to the Illinois state line, and it is al- 

 most certain that the species will eventually 

 be found in Illinois. At present it is known 

 from Georgia, Indiana, Kentucky and Ten- 

 nessee. 



Guanis Group 



Hydropsyche cuanis Ross 



Hydropsyche cuanis Ross (1938^, p. 147); 

 cT, 9. 



Larva. — Fig. 350. Length 15 mm. *Head 

 and thoracic sclerites bright brownish yel- 

 low, the head with an irregular, fine, red- 

 dish brown pattern, the pronotum with fine, 

 reddish brown speckling; legs yellow. Frons 

 almost fiat, the apical margin straight. Dor- 

 sum of abdomen, especially on the seventh 

 and eighth segments, with conspicuous flat- 

 tened setae interspersed among the simple 

 appressed ones. 



Adults. — Length 10-11 mm. Head and 

 body black with irregular areas of reddish 

 brown ; antennae with V-marks faint ; wings 

 with a purplish cast, mottled with various 

 shades of brown and without a definite pat- 

 tern. Male genitalia, fig. 369, with tenth 

 tergite simple and hoodlike, divided into a 

 pair of round lobes; claspers with apical 

 segment oblique at apex; aedeagus curved, 

 rounded at apex, incised on the meson. Fe- 

 male, fig. 386, with eighth tergite having 

 only a very short and inconspicuous apical 

 ventral fringe, eighth sternite with apico- 

 mesal corner only moderately produced, fig. 

 388C. Ninth tergite, fig. 386C, very similar 

 to that in scalaris group. 



Most of our Illinois records of this spe- 

 cies are from various points along the Kan- 

 kakee River; in addition we have taken it 

 from two other points in the extreme north- 

 eastern corner of the state. The larvae are 

 extremely abundant in swift rapids of the 

 Kankakee River at Wilmington, and here 

 we have taken large flights of the adults. 

 In this locality the spring emergence, during 

 May, is very heavy. Adults continue to 

 emerge later in the year until August but 

 never in the large numbers that we have 

 taken in May. 



The range of the species appears to be 

 very restricted, the known records including 

 only Illinois, Indiana and Michigan. 



