210 



Illinois Natural History Survey Bulletin 



Vol. 23, Art. 1 



era occur in Illinois. A large number of the 

 species are widespread, some of them Hol- 

 arctic. It is certain that a study of the 

 Holarctic fauna of this family will show a 

 good many more of the names based on 

 North American material to be synonyms 

 of European or Asiatic names. 



In the entire family the pupal chamber 

 has a slit and not a mesh in the closing cap 

 at both ends. Through these slits the pupa 

 pushes out all the larval sclerites, so that 

 it is impossible to get associations of adult 

 structures and larval sclerites in the same 

 case. For this reason it is necessary to 

 rear larvae in cages in order to associate 

 immature and adult stages. 



KEY TO GENERA 

 Larvae 



1. Middle legs with claw stout and hook 



shaped, tarsus bent, fig. 714; case 



transparent Leptocerus, p. 212 



Middle legs with claw slender, slightly 

 curved, tarsus straight, fig. 715; 

 case seldom transparent 2 



2. Maxillary palpi nearly as long as stipes, 



fig. 717; mandibles long, sharp at 

 apex, the teeth considerably below 



apex Oecetis, p. 236 



Maxillary palpi short, about half 

 length of stipes, fig. 718; mandibles 

 shorter, blunt at apex, the teeth 

 near or at apex 3 



3. Head with a suture-like line parallel- 



ing the epicranial arms, fig. 764. . . . 



Athripsodes, p. 221 



Head without a suture-like line in ad- 

 dition to the epicranial arms, fig. 811 4 



4. Mesonotum membranous with a pair 



of sclerotized, narrow, curved or 



angled bars, figs. 764, 769 



Athripsodes, p. 221 



Mesonotum without such a pair of 

 sclerotized bars, fig. 836 5 



5. .Anal segment developed into a pair of 



sclerotized, concave plates, with 

 spinose dorso-lateral and mesal 

 carinae, and an overhanging ventral 



flap, fig. 719 PSetodes, p. 256 



Anal segment convex and without car- 

 inae between anal hooks, fig. 720. . 6 



6. Hind tibiae entirely sclerotized, with- 



out a fracture in middle, fig. 716; 



abdomen without gills 



Leptocella, p. 213 



Hind tibiae with a fracture near mid- 

 dle which appears to divide tibiae 

 into two segments, fig. 715; abdomen 

 with at least a few gills 7 



Fig. 714. — Leptocerus americanus larva, 

 middle leg. 



Fig. 715. — Mystacides sepulchralis larva, 

 hind leg. 



Fig. 716. — Leptocella Candida larva, hind 

 leg. 



Fig. 717. — Oecetis cinerascens larva, head; 

 St, stipes. 



Fig. 718. — Leptocella Candida larva, head; 

 St, stipes. 



Fig. 719. — Setodes sp. larva, anal segment. 



Fig. 720. — Mystacides sepulchralis larva, 

 anal segment. 



7. Hind tibiae with a regular fringe of 



long hair, as in fig. 716 



Triaenodes, p. 244 



Hind tibiae with only irregularly 



placed hairs, fig. 715 



Mystacides, p. 253 



Pupae 



1. Anal appendages wide at base with a 

 sharp mesal corner, the apex taper- 

 ing gradually to a sharp point, fig. 

 721 Leptocerus, p. 212 



