August, 1944 



Ross: Caddis Flies of Illinois 



115 



The larvae and pupae are readily distin- 

 guished from other members of the family 

 by characters used in the key. The adults 

 may be distinguished also by the large, 

 slender outline, extremely long antennae, 

 and the polished, brightly colored and pat- 

 terned wings. 



The species frequent large, rapid rivers. 

 The larvae, which may attain a length of 

 nearly an inch, frequently net together large 

 areas of small and medium sized stones if 

 a large number of larvae spin their retreats 

 close together. Only three species have been 

 described for Nearctic America. Two of 

 them have been taken in Illinois, and the 

 other occurs in Indiana not many miles 

 away. At some time we may expect to find 

 adults of this third species which have drift- 

 ed into Illinois. 



KEY TO SPECIES 

 Larvae 



1. Head yellow, the posterior portion of 



the dorsal flange raised into a pair 



of tubercles, fig. 417 



transversum, p. 117 



Head reddish brown, the posterior 

 portion of the dorsal flange even, 

 not tuberculate, fig. 416 2 



2. Tubercles near eye larger, fig. 416. . . 



Carolina, p. 1 1 6 



415 



416 



Fig. 415. — Macronemum zebratum larva, 

 head. 



Fig. 416. — Macronemum Carolina larva, 

 head. 



Fig. 417. — Macronemum traiisdersiim larva, 

 head. 



Tubercles near eye smaller, fig. 415 . 

 zebratum, p. 115 



Adults 



1. Wings pale yellow with narrow, trans- 

 verse brown stripes 



transversum, p. 117 



Wings brown with large yellow spots 

 and stripes, fig. 420 2 



Fig. 418. — Macronemum zebratum, head. 

 Fig. 419. — Macronemum Carolina, head. 



2. Eyes small, malar space large, fig. 418 



zebratum, p. 1 1 5 



Eyes large, malar space narrow, fig. 

 419 Carolina, p. 116 



Macronemum zebratum (Hagen) 



Macronema zebratum Hagen (1861, p. 285); 

 &, 9. 



Larva. — Fig. 415. Length 22 mm. Head, 

 thoracic sclerites and legs reddish brown. 

 Head with a sharp, U-shaped ridge sur- 

 rounding a flat area embracing almost all 

 the dorsal portion of the head, this ridge 

 elevated into a distinct tubercle above each 

 eye. Mandibles with base very large and 

 apex narrow, fig. 288. Front legs with a 

 heavy brush on the tibiae. 



Adults. — Fig. 420. Length 15-18 mm. 

 Color of head and thorax metallic bluish 

 brown; antennae dark brown at base, grad- 

 ually becoming lighter toward apex; mouth- 

 parts and legs yellow. Front wings brown 

 with yellow markings forming a pattern as 

 in fig. 420. Eyes small, fig. 418, malar space 

 large. Male genitalia with parts simple, 

 fig. 421. 



In Illinois we have taken this species at 

 many localities in the northern half of the 

 state, particularly along the Fox, Kankakee, 

 Rock and Mississippi rivers. We have taken 

 the larvae and pupae very abundantly in 

 the rapids of the Kankakee River. Adult 

 emergence begins during the latter part of 

 May and continues into September. During 



