32 



Illinois Natural History Survey Bulletin 



Vol. 23, Art. 1 



short antennae, very simple and similar 

 front and hind wings and five-segmented 

 maxillary palpi in both sexes. 



Rhyacophila Pictet 



Rhvacophila Pictet (1834, p. 181). Geno- 

 type, here designated: Rhyacoph.la vul.ans 

 Pictet. 



In Illinois we have taken five species of 

 this genus. Four of them occur in streams 

 which are temporary but which are rapid 

 and clear when running; the fifth occurs m 

 a set of small, clear, ^P""^-/^^,^'^^"^!'.^ 

 at Elgin. Over 70 species of Rhyacophila 

 inhabit North America, most of them re- 

 stricted to the rapid, clear streams of 

 mountainous terrain or northern country. 



Westwood (1840, p. 51) hsts vuhata 

 Pictet as the genotype. This is undoubtedly 

 an emendation of vulgaris Pictet, since Pic- 

 tet did not list a species by the name of 

 vuhata in his description of Rhyacophila. 



KEY TO SPECIES 

 Larvae 



1 Second segment of anal larvapods with 

 a long, bladelike, dorso-lateral spur, 



f^ m fuscula, p. ^b 



Second segment of larvapods without a ^ 



distinct spur, fig. 112 



2. Second segment of maxillary palpus 



much longer than first, fig. 115. .. . 



Second segment of maxillary palpus 



not longer than first, fig. 114 



glaberrima, p. 



3 Front and middle legs almost the same 

 size and shape, fig. 116; baso-ventral 

 sclerotized rod of anal prolegs pro- 

 duced into a short, sharp, curved 



hook, fig. 91 lobifera,p 



Front femora much stouter than mid- 

 dle femora, giving the two legs dif- 

 ferent shapes, fig. 117; baso-ventral 

 sclerotized rod of anal prolegs not 



hooked, fig. 112 "^ 



4. Head wide and short, fig. 118; anal 

 hooks without teeth on inner mar- 

 gin, fig. 113 ■ 



ledra, p. 37; fenestra, p. 36 



Head narrower and longer, fig. 119; 

 anal hooks with at least one small 

 inner tooth, fig. 112 vibox, p. 36 



8 



Apex of abdomen cylindrical (females) 

 1 \mca\ segment of clasper deeply in- 

 cised to form a long dorsal point, 



fig. 120 lobifera p. 35 



Apical segment of clasper either only 



35 



35 



Adults 



1. Apex of abdomen with long claspers 

 (males) 



Tt(^n-,:^-~ 119 



Fig. IW.^Rhyacophiii fuscula larva, ana 



leg 



Fig. \\2.— Rhyacophila vibox larva, anal leg 

 Fig'. lU.— Rhyacophila fenestra larva, ana 



leg. , . , 



Fig. lU.— Rhyacophila glaberrima larva 



maxilla and labium; mp, maxillary palpus. 

 Fig. \\5.— Rhyacophila fenestra larva, max 



ilia and labium; mp, maxillary palpus. 



Fig. Wd.— Rhyacophila lobifera larva, tron 



and middle legs. 



Fig. m.— Rhyacophila fenestra larva, tror 



and middle legs. 



Fig. n%.— Rhyacophila fenestra larva, head 

 Fig. 119. — Rhyacophila vibox larva, head. 



