August, 1944 



Ross: Caddis Flies of Illinois 



265 



Neoallotype, female. — Same data as for 

 neot)'pe. 



In Illinois we have taken this species at 

 several widely scattered points. The larvae 

 are restricted to the rapid riffles of some of 

 our better streams such as the Kankakee 







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Fig. 904. — BrachycenlrHS numerosus, case. 



River and Quiver Creek. There is only 

 one generation a year, adult emergence 

 taking place in late April and early May. 

 The season timing of the species seems to 

 be remarkably acute. 



At Momence we have taken the adults 

 in great swarms, although not in the clouds 

 recorded by Say. Larval and adult associa- 

 tions have been made from pupae collected 

 from both Quiver Creek near Havana, Illi- 

 nois, and the Kankakee River at Momence. 



This is the species recorded by Betten 

 (1934) as Brachycentrus nigrosoma. The 

 type of Banks' species is a female, and it 

 seems advisable at the present to consider 

 it of doubtful identity. 



The range of the species is poorly known, 

 but it is widespread through many of the 

 northern and central states. We have rec- 

 ords from Illinois, Indiana, Maryland, Mas- 

 sachusetts, New York, North Carolina, 

 Quebec and Wisconsin. 



Illinois Records. — Duncans Mills, 

 Spoon River: Sept. 2, 1910, 1 larva. Gar- 

 den Prairie: Aug. 13, 1926, 1 larva. Ha- 

 vana, Quiver Creek: Aug. 7, 1895, C. A. 

 Hart, 9 larvae; June 11, 1896, E. B. Forbes, 



1 larva; July 3, 1896, C. A. Hart, many 

 larvae; April 24, 1898, C. A. Hart, U, 



2 9 ; Aug. 25, 1910. 1 larva; May 28, 1936, 

 Mohr & Burks, 1 larva; May 29, 1936, 

 Mohr & Burks, many larvae; June 5, 1936, 

 Mohr & Burks, \i (reared), 3 larvae, 2 

 pupae; June 20, 1936, Mohr & Burks, 6 

 larvae. Havana: White Oak Run, Oct. 

 5, 1910, rapid current, 2 larvae; June 20, 



1936, Mohr & Burks, 6 larvae. Mahomet, 

 Sangamon River: June 6, 1940, Ross & 

 Riegel, 4 larvae. Momence: May 26, 1936, 

 H. H. Ross, 2 larvae; Aug. 15, 1937, Ross 

 & Burks, 6 larvae; Oct. 27, 1938, Ross & 

 Burks, many larvae; Nov. 3, 1938, Mohr 

 & Burks, many larvae; Dec. 21, 1938, 

 Mohr & Burks, 6 larvae; May 7, 1940, B. 

 D. Burks, $ $, 9 9; May 8,' 1940, Mohr 

 & Burks, 7 pupae, 5 9 ; preceding Momence 

 records are from Kankakee River; July 14, 

 1936, B. D. Burks, many larvae; Aug. 21, 



1936, Ross & Burks, 3 larvae; May 4, 



1937, Ross & Mohr, $ $, 9 9,3 mating 

 pairs. 



Brachycentrus lateralis (Say) 

 Phryganea lateralis Say (1823, p. 161). 



Larva. — Fig. 897. Length 12 mm. Head, 

 thoracic sclerites and legs yellowish, head 

 with three black lines on dorsum, femora 

 with upper and lower edges black. Struc- 

 tures similar to those of numerosus. 



Case. — Length 12 mm. Of typical log- 

 cabin construction as for numerosus. 



Adults. — Length 9-1 1 mm. Color chiefly 

 black with tawny wings as with numerosus. 

 Male genitalia, fig. 900: cerci not fused on 

 meson but close enough to appear hoodlike; 

 claspers with narrow base, fairly long neck, 

 the apex widened, the posterior face con- 

 cave and with a short, sharp tooth; tenth 

 tergite short, emarginate at apex and 

 humped dorsally; aedeagus tubular. Female 

 genitalia simple, similar to those of numer- 

 osus in general proportions. 



Neotype, male. — Momence, Illinois: 

 May 4, 1937, Ross & Mohr. 



Neoallotype, female. — Momence, Illi- 

 nois: May 17, 1937, Ross k Burks. 



In recent years this species has been found 

 in Illinois at Momence only, where it is 

 abundant in the Kankakee River. It has 

 a very definite place in the seasonal suc- 

 cession about 2 weeks after the peak of 

 numerosus. 



We have not reared the larva of lateralis, 

 but there seems to be no doubt that the 

 larva described above belongs to this species. 

 It occurs abundantly in the Kankakee River 

 along with larvae of numerosus, differing 

 only in a tendency to prefer deeper and less 

 rapid points in this stream. We have made 

 many collections at Momence, where these 

 two species occur, and have taken only the 



