30 



Illinois Natural History Survey Bulletin 



Vol. 23, Art. 1 



two-thirds distance from base of 



tibiae, fig. 74 



Brachycentridae, p. 260 



Middle tibiae without spines, their 

 tarsi with only a scattered few in 

 addition to apical ones, preapical 

 spurs of tibiae hairy, longer and situ- 

 ated at middle of tibiae, fig. 75 



Lepidostomatidae, p. 258 



RHYAGOPHILIDAE 



The adults, both sexes, of the Rhyaco- 

 philidae have five-segmented maxillary palpi. 

 Two distinct groups are included in the 

 Illinois representatives of this family; the 

 subfamily Rhyacophilinae has free-living, 

 predaceous larvae and the subfamily Glos- 

 sosomatinae has saddle-case making larvae. 

 This remarkable difference in habits of the 

 larvae has no apparent outstanding counter- 

 part in the adults. The southvi^estern genus 

 Jtopsyche has been placed in the subfamily 

 Hydrobiosinae, but until the larvae of this 

 genus are discovered its true position is 

 enigmatic. 



KEY TO GENERA 

 Larvae 



1. Anal larvapods with long, large hooks, 



figs. 22, 91. Free living without 



cases Rhyacophila, p. 32 



Anal larvapods with very small, re- 

 tractile hooks, fig. 23. Living in 

 saddle-shaped cases constructed of 

 small stones 2 



2. Pronotum notched only at extreme 



antero-lateral angle, at which point 



the legs are attached, fig. 92 



Glossosoma, p. 39 



Pronotum narrow from anterior mar- 

 gin to middle, the legs attached at 

 this central point, fig. 93 3 



3. Dorsal plate of last segment with 4 



long, apical setae; pronotum with 

 only a few scattered setae; anal hook 

 divided into many teeth, fig. 96. . . 



Protoptila, p. 41 



Dorsal plate of last segment with 6 

 long, apical setae, fig. 94; pronotum 

 with a line of setae near posterior 

 margin, and with a brush of setae 

 along each anterior corner, fig. 93; 

 anal hook with only 1 large and 1 

 small tooth, fig. 95 Agapetus, p. 39 



Pupae 



1. Mandibles with inner margin minutely 

 serrate, and with apical inner tooth 



Fig. 91. — Rhyacophila lobijera larva, anal 

 hook. 



Fig. 92. — Agapetus illini larva, pronotum. 



Fig. 93. — Glossosoma intermedium larva, 

 pronotum. 



Fig. 94. — Agapetus illini larva, plate of 

 tenth tergite. 



Fig. 95. — Agapetus illini larva, anal hooks. 



Fig. 96. — Protoptila lega larva, anal hooks. 



Fig, 97. — Rhyacophila lobijera pupa, mandi- 

 bles. 



Fig. 98. — Protoptila lega pupa, left mandible. 



Fig. 99. — Agapetus illini pupa, left mandi- 

 ble. 



Fig. 100. — Glossosoma intermedium pupa, 

 left mandible. 



Fig. 101. — Protoptila lega pupa, head, ven- 

 tral aspect. 



