154 



Illinois Natural History Survey Bulletin 



Vol. 23, Art. 1 



aedeagus large, with a large spiral and the 

 apical portion straight at tip. Female geni- 

 talia, fig. 535: eighth tergite with apex 

 widely and deeply emarginate and with a 

 sclerotized nodule at base of depression; 

 sternite with a long, bell-shaped central 

 plate and with the apical margin undulate 

 to form a pair of low, lateral humps and 

 a higher mesal projection. 



The species icona, described from Mexico 

 and since taken in Texas and Oklahoma, 

 might be confused with this species, but 

 icona differs radically in having short clasp- 

 ers, fig. 526. 



This is one of the more common Illinois 

 species of the genus, having been taken in 

 large numbers in a considerable variety of 

 creeks and small rivers in the northern half 

 of the state. Larvae and pupae have been 

 collected in several localities. The adults 

 appear throughout the warmer months, from 

 May through September. 



The range of the species extends from 

 Oklahoma to New York, with Illinois as 

 the apparent density center. We have rec- 

 ords for Illinois, Indiana, New York and 

 Oklahoma. 



Illinois Records. — Many males and fe- 

 males and four pupae, taken May 24 to 

 September 20, and many larvae, taken May 

 21 to June 6, are from Amboy (Green Riv- 

 er), Apple River Canyon State Park, Downs 

 (Kickapoo Creek), Howardsville, Kappa 

 (Mackinaw River), Mount Carroll, Mun- 

 cie, Oakwood (Middle Fork, Vermilion 

 River, Salt Fork River), Quincy (stream 

 near Cave Spring, Burton Creek), Rock 

 City, Serena, Spring Grove, White Pines 

 Forest State Park. 



Neotrichia Morton 



Cyllene Chambers (1873, p. 124); preoccu- 

 pied. Genotype, monobasic: Cyllene minutisi- 

 mella Chambers. 



Neotrichia Morton (1905, p. 72). Genotype, 

 monobasic: Neotrichia collata Morton. 



Exitrichia Mosely (1937, p. 170). Genotype, 

 by original designation: Exitrichia anahua 

 Mosely. 



Dolotrichia Mosely (1937, p. 177). Genotype, 

 by original designation: Dolotrichia canixa 

 Mosely. 



Guerrotrichia Mosely (1937, p. 179). Geno- 

 type, by original designation: Guerrotrichia 

 caxima Mosely. 



Lorotrichia Mosely (1937, p. 181 J. Geno- 

 type, by original designation: Lorotrichia hi- 

 aspa Mosely. 



This genus contains the smallest caddis 

 flies in North America. Of the 11 species 

 known from the United States, 6 have been 

 captured in Illinois. All the species frequent 

 clear-water streams, and some of them are 

 extremely local in their distribution. The 

 genus has developed a large fauna in the 

 Neotropical region, which seems to be the 

 center of distribution for many "micros" 

 that range from southern Mexico to Okla- 

 homa, Illinois and New York. 



Characters of the genitalia separate the 

 species in both males and females, but, to 

 date, reliable characters have not been found 

 for separating the larvae. We have associ- 

 ated larvae and adults of minutisimella, 

 okopa, collata and riegeli. 



KEY TO SPECIES 

 Adults 



1. Apex ot abdomen with several sets of 



plates or processes (males) 2 



Apex of abdomen simple and tubular 

 (females) 9 



2. Ninth segment with outer lateral proc- 



ess B divided to form long dorsal 

 and ventral fingers; plate E behind 

 claspers twice as long as claspers, 



fig. 542 kitae, p. 158 



Ninth segment with outer lateral proc- 

 ess simple; plate behind claspers 

 short or inconspicuous, figs. 543- 

 549 3 



3. Aedeagus with a pair of stout, sclero- 



tized hooks, figs. 543-545 4 



Aedeagus without stout, sclerotized 

 hooks, figs. 546-549 6 



4. Claspers slender, almost three times 



longer than wide, fig. 543 



collata, p. 159 



Claspers almost quadrate, no longer 

 than wide, fig. 544 5 



5. Aedeagus with both sclerotized hooks 



subequal and alike; apex of claspers 



with a steplike break, fig. 544 



falca, p. 159 



Aedeagus with sclerotized hooks very 

 dissimilar in length and shape; 

 apex of claspers truncate, fig. 545. . 

 riegeli, p. 159 



6. Aedeagus ending in a uniform, sclero- 



tized cylinder; claspers heavily 



sclerotized and black, fig. 546 



okopa, p. 1 58 



Aedeagus not cylindrical or sclero- 

 tized at apex; claspers not as above, 

 fig. 547 -. 7 



7. Claspers fused to form a long ventral 



