August, 1944 



Ross: Caddis Flies of Illinois 



213 



Abdominal gills absent. Anal segment in- 

 cised on meson, with brushes of black setae 

 along the sides of the incision. 



Case. — Length 7-8 mm. ; slender, slightly 

 curved and made entirely of secretion; pale 

 green to straw color. 



'*li.: -..:;......: 1 lllln. ,■ ;,||||f 



Fig. 742. — Leptocerus americanus larva. 



Adults. — Length 8 mm. Body very slen- 

 der, dark brown in color. Both wings nar- 

 row and pointed. Male genitalia, fig. 743, 

 with tenth tergite long and bladelike, aedea- 

 gus irregular; claspers short, narrow at 

 base and expanding rapidly into a large, 

 spatulate structure. Female genitalia, fig. 

 743, with tenth tergite large and semimem- 

 branous, lobes of the ninth tergite large and 

 clasper-like, and bursa copulatrix small and 

 somewhat circular. 



This species is distributed over all parts 

 of Illinois but has been taken in large num- 

 bers around only the glacial lakes and in 

 the slow streams connecting them. In these 

 places the larvae are almost invariably found 

 in water horsetail. 



Illinois Records. — Many males, females 

 and pupae, taken May 6 to August 2, and 

 many larvae, taken May 15 to June 12, 

 are from Antioch, Carbondale, Channel 

 Lake, Eflfingham, Eichorn (Hicks Branch), 

 Fox Lake (Pistakee Bay), Fulton, Grand 

 Tower, Grass Lake, Havana (Devil's 

 Hole), Herod, McHenry, Momence, Olive 

 Branch (Horse Shoe Lake), Ottawa, Pista- 

 kee Lake, Putnam (Lake Senachwine), 

 Richmond, Savanna, Springfield, Wads- 

 worth (Des Plaines River), West Havana, 

 Zion (Dead River). 



Fig. 743. — Leptocerus americanus^ genitalia. 

 Ay male; 5, female. 



Leptocella Banks 



Leptocella Banks (1899, p. 214). Genotype, 

 by original designation: Mystacides iiwarowii 

 Kolenati. 



In this genus the case and larva are 

 always very long and narrow. The larva 

 has a long, triangular gula, short mandibles 

 with a broad apex divided into three or 

 four teeth, and undivided tibiae. Hind legs 

 with or without swimming brush. 



The adults are very long and slender, 

 chiefly white or gray, frequently with con- 

 spicuous patterns. They include some of our 

 most beautiful caddis flies. This is the only 

 genus in which it is essential to have mate- 

 rial pinned instead of preserved in liquid. 

 For satisfactory results the specimens must 

 be handled extremely carefully. To obtain 

 good study material, it is necessary to kill 

 them a few at a time in a strong cyanide 

 bottle, remove them to a temporary con- 

 tainer where they will not rub, and then pin 

 them up very carefully at the first oppor- 

 tunity, taking pains at all times to avoid 

 rubbing off the hairs on the wings. These 



