126 



Illinois Natural History Survey Bulletin 



Vol. 23, Art. 1 



Ochrotrichia Mosely (1934/^, p. 162). Geno- 

 type, by original designation: Ochrotrichia in- 

 siilaris Mosely. 



The genus Polytrichia, erected in 1926 

 for the species Ithytrichia confusa, is pre- 

 occupied by a genus of snails and therefore 

 cannot be used in the caddis flies. It is neces- 

 sary to resurrect the genus Ochrotrichia, 

 described in 1934, with insularis as its type. 

 In 1937 Mosely sank his genus Ochrotrichia 

 as a synonym of Polytrichia, but now Mose- 

 ly's name must be applied to the large as- 

 semblage of species in North, Central and 

 South America which have previously been 

 placed under Polytrichia. 



Ten of the 20 described Nearctic species 

 have been taken in Illinois and one or two 

 more may show up with additional collect- 

 ing. All the species frequent clear and 

 rapid streams, including some which dry in 

 summer. Many of the species appear to 

 be local in distribution, and the few known 

 localities for any one of these species may 

 be widely separated. 



KEY TO SPECIES 

 Larvae 



1. Abdominal tergites, fig. A6AA, with an 



ovoid sclerite having a transverse, 

 membranous center and with lateral, 

 sclerotized, setate spots some dis- 

 tance from mesal sclerite; case tor- 

 toise-like, flat on the bottom 



riesi, p. 132 



Abdominal tergites, fig. 4645, orna- 

 mented only with inconspicuous 

 sclerotized rings; case purselike, fig. 

 465 2 



2. Head and thoracic sclerites almost en- 



tirely yellow or light brownish yel- 

 low, sometimes with a faint reddish 

 tone 3 



Head and thoracic sclerites mostly 

 dark brown, sometimes shading to 

 black 4 



Fig. 464. — Ochrotrichia larvae, abdominal 

 rings. A, 0. riesi; B, 0. anisca. 



Fig. 465. — Ochrotrichia unio, larva and case. 



3. Thoracic sclerites with distinct mark- 



ings of fairly dark brown 



tarsalis, p. 130 



Thoracic sclerites with only indistinct 

 suffusions of darker color; head and 

 thorax frequently with a reddish 

 tone anisca, p. 131 



4. Head with a small, mesal pale spot or 



stripe xena, p. 130 



Head without a mesal pale area 



unio, 



p. 129; eliaga, p. 132; spinosa, p. 132 



Adults 



1. Apex of abdomen with long claspers, 



fig. 466 (males) 2 



Apex of abdomen tubular, fig. 478 (fe- 

 males) 12 



2. Tenth tergite triangular or vasiform, 



figs. 466, 467, small, without long or 

 hooked, sclerotized processes; both 

 ninth segment and claspers long and 



narrow 3 



Tenth tergite longer, with a set of defi- 

 nite, heavily sclerotized hooked or 

 straight processes, fig. 471; ninth 

 segment and claspers shorter 4 



3. Claspers with two mesal brushes of 



black pegs at apex, fig. 466; tenth 



tergite triangular xena, p. 130 



Claspers with only one mesal brush of 

 black pegs at apex, fig. 467; tenth 

 tergite vasiform unio, p. 129 



4. Claspers shoelike, upcurved at apex, 



dorsal margin concave, fig. 468. ... 5 

 Claspers sinuate, fig. 475 8 



5. Left side of tenth tergite with a large, 



conspicuous spine near middle, 

 curved mesad, fig. 471. . .tarsalis, p. 130 

 Left side of tenth tergite without such 

 a spine curved mesad 6 



6. Tenth tergite with spine C filamentous 



and not angled from its base, fig. 



468 shawnee, p. 131 



Tenth tergite with spine C stout, 

 curved away from and back to its 

 parent sclerite, fig. 469 7 



7. Tenth tergite with sclerite A very 



broad, D almost touching spiral of 



