August, 1944 



Ross: Caddis Flies of Illinois 



99 



many larvae; Middle Fork River, July 18, 

 1933, Ross & Mohr, 1 6 ; Sept. 20, 1935, 

 DeLong & Ross, 7 c5 , 9 9 ; May 21, 1936, 

 Mohr & Burks, 1 larva, 1 pupa; Salt Fork 

 River, Aug. 25, 1936, H. H. Ross, many 

 larvae; Middle Fork River, July 14, 1939, 

 Burks & Riegel, 2 larvae. 



Hydropsyche slossonae Banks 



H\d)opsvche slossonae Banks (1905i^, p. 14); 



Larva. — Fig. 355. Length 16 mm. Head, 

 thoracic sclerites and legs dark brown, fre- 

 quently approaching black, with the fol- 

 lowing areas yellowish: retracted posterior 

 portion of head, one or two small quadrate 

 marks on the dorso-mesal line, and irregular 

 portions of the legs; abdomen purplish gray. 



Adults. — In size, color and general struc- 

 ture similar to bifida. Male genitalia, fig. 

 362, with the apical processes of the tenth 

 tergite long, enlarged at middle, the mesal 

 face concave, and the two forming a horse- 

 shoe-like structure; claspers with apical seg- 

 ment long, narrow and curved mesad; 

 aedeagus with base large, markedly sinuate, 

 the dorsal membranous lobes tipped by a 

 short, sharp spur, and with the apical bulb 

 provided with one mesal and two lateral 

 pockets of spicules. Female typical for the 

 bifida group, genitalia as in fig. 387G. 



In Illinois we have records for this species 

 from only three localities. One of these is 

 the small stream at Elgin fed by Rainbow 

 Springs, in which this species was taken 

 in great abundance. Our Illinois collec- 

 tions, supplemented by those from other 

 states, show that the adult emergence occurs 

 from May to August. The larval head 

 pattern is diagnostic. 



The range of this species, fig. 16, includes 

 most of the northeastern states. We have 

 records from Illinois, Michigan, Minnesota, 

 New Hampshire, New York, North Caro- 

 lina, Pennsylvania, Saskatchewan and Wis- 

 consin. 



Illinois Records. — Elgin, Rainbow 

 Springs: April 19, 1939, Burks & Riegel, 

 many larvae; May 9, 1939, Ross & Burks, 

 many larvae, 4^,2$, 1 pupa ; June 6, 1939, 

 Burks & Riegel, $ $ , ? 9 ; Aug. 9, 1939, 

 Burks & Riegel, 3 <? ; April 25, 1941, Ross 

 & Burks, many larvae; May 7, 1941, Mohr 

 k Burks, 1 larva. Galena: June 28, 1892, 

 Hart & Shiga, 2 i pupae. Spring Grove: 

 May 29, 1938, Mohr & Burks, 1 i . 



Hydropsyche recurvata Banks 



Hydropsyche slossonae var. recurvata Banks 

 (1914, p. 253); &. 



Hydropsyche codona Betten (1934, p. 187); 



cf , 9. 



Larva. — Length 14 mm. Head varying 

 from the dark checkered pattern in fig. 356 

 to almost entirely yellow with a few brown 

 markings outlining a skeleton checkerboard, 

 fig. 357; thoracic sclerites and legs usually 

 entirely yellow with a few dark lines, vary- 

 ing to brownish yellow. 



Adults. — In size, color and general struc- 

 ture similar to bifida. Male genitalia, fig. 

 363, with apical processes of tenth tergite 

 short; claspers with apical segment short, 

 conical and pointed; aedeagus with stem 

 long and nearly straight, dorsal membra- 

 nous lobes tipped by a stout recurved spur 

 (rarely absent or reduced) and with the 

 apical bulb forming a pair of membranous 

 lobes, each with a pocket of spicules. Female 

 genitalia typical for members of the bifida 

 group, ninth tergite as in fig. 387C. 



Of unusual interest is our only Illinois 

 larval record of this species. At Evanston 

 we found the larvae and pupae under rocks 

 in Lake Michigan, in water which was 2 

 to 3 feet deep at that time. A few adults 

 were taken around buildings along the 

 beach. Collecting in situations away from 

 Lake Michigan has persistently failed to 

 disclose representatives of this species in 

 the state. 



The species is normally taken in swift, 

 cold rivers to the north, fig. 16, including 

 Michigan, Minnesota, New York, Ontario, 

 Quebec, Saskatchewan and Wisconsin, with 

 adult emergence occurring from May to 

 September. 



Illinois Records. — Evanston, Lake 

 Michigan: May 22, 1938, Ross & Burks, 

 3 (3 , 1 $ , many pupae and larvae. Wauke- 

 GAN, Lake Michigan: June 9, 1938, at light, 

 Ross & Burks, 2 c? , 19. 



Depravata Group 

 Hydropsyche betteni Ross 

 Hydropsyche betteni Ross (1938a, p. 146); 



Larva. — Fig. 348. Length 16 mm. Head 

 and thoracic sclerites dark brown, frequent- 

 ly approaching black, with a light spot sur- 



