236 



Illinois Natural History Survey Bulletin 



Vol. 23, Art. 1 



turn and legs very pale yellowish brown, not 

 much darker than the straw-colored body; 

 upper portion of head with scattered brown 

 spots; parafrontal areas nearly as wide as 

 frons. Mesonotum with only a few hairs in 

 addition to lateral tuft of two or three 

 hairs. Ninth segment with only one or two 

 pairs of very weak, short setae. Case with 

 lateral margins somewhat produced, al- 

 though not as much so as in ancylus; con- 

 structed of sand grains and fairly smooth. 

 We have a single collection from Apple 

 River in Apple River Canyon State Park, 

 Illinois, June 27, 1940, Mohr & Riegel. 



Species c. — Length 8.5 mm. Head, pro- 

 notum and legs chocolate brown, the head 

 with many light dots and dashes. Para- 

 frontal areas only about half width of frons. 

 Mesonotum with only a few scattered hairs 

 in addition to lateral tufts composed of one 

 or two hairs; sclerotized bars wide, sharply 

 angled and almost L-shaped. Ninth seg- 

 ment with two pairs of long black hairs. 

 Anal legs with long, dorsal sclerotized bars. 

 Case made of flat stones, stout and almost 

 cylindrical. These larvae have been col- 

 lected in Lake Erie at Put-in-Bay, Ohio, 

 and may be either resurgens or one of the 

 punctatus group. They are conspicuous in 

 that the abdomen is large and cylindrical, 

 scarcely tapering toward apex. They were 

 collected in deep water. 



Oecetis McLachlan 



Oecetis McLachlan (1877, p. 329). Geno- 

 type, here designated: Leptocerus ochraceus 

 Curtis. 



Setodina Banks (1907«, p. 130). Genotype, 

 by original designation: Setodina parva Banks. 



Oecetina Banks (1899, p. 215). Genotype, 

 by original designation: Oecetis incerta of 

 American authors, nee Walker = inconspicua 

 (Walker). 



Oecetodes Ulmer (1909, p. 144). Genotype, 

 by subsequent designation of Milne (1934, p. 

 19): Setodes avara Banks. 



Friga Milne (1934, p. 16). Genotype, by 

 original designation: Setodes immobilis Hagen. 



Quaria Milne (1934, p. 17). Genotype, 

 monobasic: Oecetis scala Milne. 



Yrula Milne (1934, p. 17). Genotype, by 

 original designation: Oecetina fiimosa Banks. 



This genus is of unusual interest because 

 of the predaceous habit of the larvae and 

 the elongate, grasping type of mouthparts 

 which have been developed in company with 

 this habit. The adults may readily be 



distinguished by venation, the pupae by the 

 mandibles and anal appendages. 



In this genus we have possibly the most 

 widely distributed caddis flies in North 

 America and species which become abundant 

 in very diverse situations. Only 15 species 

 have been described from North America; 

 of these we have taken 7 in Illinois. The 

 females and larvae have both exhibited 

 good key differences, but due to difficulties 

 in rearing only five larvae have been asso- 

 ciated with the adults. 



KEY TO SPECIES 

 Larvae 



1. Head brown with light spots and bars, 



fig. 811; case of log cabin type, fig. 



833 cinerascens, p. 241 



Head straw color, sometimes with 

 brown spots or bars, fig. 812; case 

 of stone construction 2 



2. Dorsal hump of first abdominal seg- 



811 



Fig. 811. 

 Fig. 812. 



812 



-Oecetis cinerascens, larva. 

 -Oecetis species a larva. 



813 



Fig. 813. — Oecetis avara larva, dorsal hump. 



Fig. 814. — Oecetis eddlestoni larva, left 

 mandible, ventral aspect. 



Fig. 815. — Oecetis species b larva, left man- 

 dible, ventral aspect. 



I 



