August, 1944 



Ross: Caddis Flies of Illinois 



85 



larvae; May 23, 1939, Burks & Riegel, 2$ , 

 1 $ , 3 larvae; June 6, 1939, Burks & Riegel, 

 4<5, 39 ; June 13, 1939, Prison & Ross, 

 3$, many larvae; Sept. 19, 1939, Ross & 

 Mohr, 3 larvae. Fountain Bluff: May 



14, 1932, Frison, Ross & Mohr, 1 ? ; May 



15, 1932, Ross & Mohr, 19. Oakwood, 

 small tributary Middle Fork River: July 

 14, 1939, Burks & Riegel, 1 larva. Utica, 

 Split Rock Brook: Feb. 1, 1941, Frison, 

 Ries & Ross, 2 larvae; May 24, 1941, Ross 

 & Burks, 1 9 . 



Stnicridea McLachlan 



Smicridea McLachlan (1871, p. 134). Geno- 

 type, here designated: Smicridea Jasciatella 

 McLachlan. 



This genus has not yet been recorded from 

 Illinois. The genotype has been taken com- 

 monly in Texas and Oklahoma and may 

 ultimately be found in southern Illinois. 

 The distinctive larval mandibles, fig. 287, 

 pupal mandibles and apical processes, figs. 

 309, 316, adult venation, fig. 330, and male 

 genitalia, fig. 340, will readily identify this 



c^. 



Fig. 340. — Smicridea Jasciatella, male genitalia. 



species. The larvae have been collected in 

 small spring-fed streams in both Texas and 

 Oklahoma. I have found the adults especi- 

 ally abundant in this latter state. 



Potamyia Banks 



Potamyia Banks (1900a, p. 259). Genotype, 

 by original designation: Macronema flavum 

 Hagen. 



Only one species of this genus is known. 

 In structure the female is very similar to 

 that of Hydropsyche, but the male, larva 

 and pupa are so distinctive that there is no 

 question as to the separate generic status 

 of Potamyia. 



Potamyia flava (Hagen) 



Macronema flavum Hagen (1861, p. 285); 



Hydropsyche kansensis Banks (1905^, p. 15); 



Larva. — Length 13 mm. Head, thoracic 

 sclerites and legs brownish yellow, the 

 frontal area of head with a reddish cast, 

 and the thoracic sclerites bordered by a 

 narrow, black line. Frons subtriangular. 

 Mandibles, fig. 283, with long, wide, lateral 

 flanges along basal half. Hair on abdomen 

 short and appressed. 



Adults. — Length 10-11 mm. Color al- 

 most uniformly light brownish yellow, with 

 a slight pinkish tinge. Male with very long, 

 slender antennae and without spurs on the 

 front tibiae; male genitalia, fig. 341, with 

 simple parts. Female with shorter antennae 

 and normal spurs on front tibiae, in both 

 these respects resembling Hydropsyche. 



This is one of the most common large- 

 stream to large-river species, not only in 

 Illinois but throughout the Middle West. 

 We have abundant records of the species 

 from all parts of Illinois and have taken 

 it repeatedly in huge swarms along such 

 rivers as the Illinois, Mississippi, Ohio and 

 Rock. The adults begin emerging in May 

 and continue through September. 



An interesting feature of the species' 

 habits has been observed in a few small 

 streams where the larvae were accessible. 

 Here it was found that, instead of hiding 

 under the rocks, the larvae tended to fre- 

 quent less rapid portions of the stream and 

 construct their retreats on top of the rocks. 

 In many of these situations their nets could 

 be seen sticking up into the current like 

 miniature fences. 



The range of the species seems to be re- 

 stricted to midwestern and southern states, 

 with a preference for the larger and slower 



Fig. 341. — Potamyia flava, male genitalia. 



