August, 1944 



Ross: Caddis Flies of Illinois 



249 



18. Apex of ninth sternite produced into a 



pair of long, slender, pointed fingers, 



fig. 856 ignita, p. 252 



Apex of ninth sternite not produced 

 into long fingers, fig. 858 19 



19. Bursa copulatrix with ventral folds 



forming long, shelflike, sclerotized 

 bands, fig. 857, and base ot apical 

 hook heavily sclerotized around 



edge species a, p. 253 



Bursa copulatrix with ventral folds 

 either straplike and not shelflike 

 or membranous, fig. 858, and base 

 of apical hook uniformly sclerotized 20 



20. Apical lobes of ninth sternite project- 



ing more sharply posterad, fig. 858; 

 a sclerotized bar, platelike at each 

 end, is situated above base ot bursa 



supports baris, p. 252 



Apical lobes of ninth sternite not pro- 

 jecting so sharply, fig. 859; only an 

 arcuate lobe above base of bursa 

 supports 21 



21. One internal told beyond base of 



clasper sclerotized, fig. 859 



flavescens, p. 251 



.AH internal folds beyond base ot 

 clasper membranous, fig. 860 22 



22. Ventro-lateral margins of ninth seg- 



ment sclerotized, flared and con- 

 voluted, fig. 860 marginata, p. 251 



Ventro-lateral margins of ninth seg- 

 ment not flared and almost entirely 

 membranous, fig. 861 tarda, p. 250 



Triaenodes frontalis Banks 



Triaenodes frontalis Banks (1907^, p. 127); 

 9. 



Not yet taken in Illinois, but is known 

 from Colorado and Saskatchewan, where it 

 frequents ponds. 



Triaenodes grisea Banks 



Triaenodes grisea Banks (1899, p. 214); 9. 



Not yet taken in Illinois. It is known 

 from Colorado, Manitoba and Saskatche- 

 wan; it frequents ponds. This and frontalis 

 might be looked for in some of the marsh 

 situations of northeastern Illinois. 



Triaenodes aba Milne 



Triaenodes sp. Milne (1934, p. 12); cf. 

 Triaenodes aba Milne (1935, p. 20); c^. 



Larva. — Fig. 837. Length 10 mm. Head, 

 pronotum and legs cream color, the head 



with a pair of dark stripes on the ventral 

 aspect, with another pair on the dorsum 

 and irregular small spots on the head and 

 pronotum; the spots on the frons forming 

 an interrupted pair of lines just inside the 

 large stripes. 



Adults. — Length 8-9 mm. Color reddish 

 brown with a narrow dorsal stripe of pink- 

 ish brown when the wings are folded in 

 repose. Male genitalia, fig. 843: tenth ter- 

 gite with only a vestigial mesal process; 

 cerci long and slender, not quite as long as 

 aedeagus; claspers with large platelike 

 mesal lobe, short lateral spur; aedeagus 

 U-shaped. Female genitalia, fig. 853 : ninth 

 sternite forming a V with wide arms and 

 a narrow cleft, from side view appearing 

 shallow and pointed at both ends; abdomen 

 thin, short and flat. 



Allotype, female. — Zion, Illinois, along 

 Dead River at Dunes Park: June 28, 1940, 

 Mohr & Riegel. 



This species is abundant in two marsh 

 areas in northeastern Illinois, one the Des 

 Plaines River at Rosecrans, the other the 

 Dead River at Zion. It was reared from 

 both localities. The larvae were found in 

 weed beds, and their cases were very diffi- 

 cult to see in the mass of broken twigs which 

 had accumulated in these areas. Betten 

 (1934, p. 287) recorded the species from 

 Lake Forest, Illinois. Our adult records 

 are for June, July and August, indicating 

 a single generation per year. 



The range of this species is poorly defined 

 but apparently includes most of the North- 

 east. Records are available from Illinois, 

 Massachusetts, Michigan, New Hampshire, 

 Ontario and Wisconsin. 



Illinois Records. — Chicago: June 16, 

 W. J. Gerhard, 2$ , FM. Fox Lake: June 

 23, 1892, Hart & Shiga, 1 9 ; June 26, 1936, 

 Frison & DeLong, 1 $ . Northern Illi- 

 nois: 1 S . Rosecrans: June 14, 1938, Ross 

 & Burks, 2 6 ; Des Plaines River, May 23, 

 1938, Ross & Burks, many larvae, 6 3 , 

 9 9 (all reared) ; May 29, 1938, Mohr & 

 Burks, 1 larva (reared) ; June 8, 1938, Ross 

 & Burks, many larvae, 1 6 ; June 9, 1938, 

 at light, Ross & Burks, 6 S ; June 13, 

 1938, Ross & Burks, 4 c$ ; June 14, 1938, 

 Ross & Burks, many larvae; June 15, 

 1938, Ross & Burks, 6S ; June 21, 1938, 

 Ross & Burks, 19. Spring Grove: Aug. 

 12, 1937, at light, Ross & Burks, 1 6 . Ur- 

 bana: Aug. 25, 1892, McElfresh, 19. 

 Wadsworth, Des Plaines River: July 7, 



