204 



Illinois Natural History Survey Bulletin 



Vol. 23, Art. 1 



the surface and with a pair of large, yellow 

 marks along the posterior margin; in repose 

 these two yellow marks form a double, 

 diamond-shaped, mesal pattern. Male geni- 

 talia, fig. 697, with ninth and tenth tergites 

 both narrow and beaked, ninth sternite 

 nearly truncate, and claspers short with a 

 long, sclerotized, constricted mesal arm 



700 



AUTUMNUS 



■-\ 





scus 



Figs. 700-701. — Neophylax, female geni- 

 talia. 



which is enlarged at tip; aedeagus simple 

 and tubular. Female genitalia, fig. 700, with 

 ninth and tenth segments narrow and small, 

 subgenital plate wide and with two pairs 

 of fairly long projections. 



This species has been found in the north- 

 ern portion of Illinois and also in the Ozark 

 Hills streams of southern Illinois. In both 

 areas it is confined to small, clear and rapid 

 streams with predominantly rock bottoms. 

 In all areas but one, adults and pupae have 

 been taken only late in the year, from Sep- 

 tember into October. The one exception 

 was a large colony in Split Rock Brook at 

 Uticaj where the adults emerged in large 

 numbers in April. The reason for this 

 deviation from the usual seasonal cycle we 

 do not know, but it is the only record of 

 adults in the spring for the entire genus 

 anywhere on the continent. 



Of unique interest is the adaptation of 

 this species to streams which become dry in 

 summer, such as those in the Ozark Hills. 

 In these situations the larvae mature at 

 least by April, fasten their cases under 



stones and aestivate until autumn; in Sep- 

 tember the larvae change to the pupae, and 

 shortly thereafter the adults emerge. When 

 the stream becomes dry, a very high pro- 

 portion of the aestivating larvae die from 

 desiccation, but those which are situated 

 under a rock which remains even slightly 

 damp are able to survive and mature. We 

 have observed successful emergence of the 

 adults at Herod when the stream was still 

 dry, the pupae leaving the moist cases with 

 no mishaps. After a stream has been dry 

 for a spring and summer, it is startling to 

 find that the next spring, when it is again a 

 rapid stream, the rocks are almost covered 

 with the larvae of this species. 



The species has not been taken very fre- 

 quently, but the records are scattered 

 through most of the Northeast; records 

 include Illinois, Michigan, New York, On- 

 tario and Wisconsin. 



It has been suggested by Betten and others 

 that this species might be the same as the 

 genotype, which was described from New 

 York. It certainly is closely related to the 

 genotype, concinnus, but until information 

 is available regarding the type, it seems 

 advisable to treat the two as distinct. 



Illinois Records. — Alto Pass, Union 

 Spring: Oct. 18, 1938, Ross & Burks, many 

 pupae and larvae; March 23, 1939, Ross 

 & Burks, many larvae; May 26, 1940, Mohr 

 & Burks, many larvae; May 31, 1940, B. 

 D. Burks, many larvae; May 12, 1939, 

 Burks & Riegel, many larvae. Belvidere, 

 Kishwaukee Creek: June 18, 1938, B. D. 

 Burks, 1 larva. Dundee: May 23, 1939, 

 Burks & Riegel, many larvae. Elgin : April 

 19, 1939, Burks & Riegel, 1 larva; May 9, 

 1939, Ross & Burks, 6 larvae; Sept. 19, 

 1939, Ross & Mohr, \$, 12; preceding 

 Elgin records are from Botanical Gardens; 

 Trout Spring, March 7, 1940, Burks & 

 Mohr, 5 larvae. Herod, Gibbons Creek: 

 March 28, 1935, Ross & Mohr, 2 larvae; 

 May 29, 1935, Ross & Mohr, many larvae; 

 Aug., 1936, Ross & Burks, many larvae; 

 April 19, 1937, 4 larvae; Sept. 11, 1937, H. 

 H. Ross, 4 larvae; Oct. 3, 1937, Ross & 

 Burks, many larvae, pupae and pupal skins; 

 and the following specimens which were 

 reared, emerging on the dates shown: Oct. 

 8, 1937, Ross & Burks, 5 pupae; Oct. 18, 

 1937, 15,19; Oct. 21, 1937, 3 $ ; Oct. 25, 

 1937, 1 ? ; Oct. 29, 1937, 6 2 ; Nov. 1, 1937, 

 1 $ ; Nov. 2, 1937, 2 $ ; Nov. 3, 1937, 1 2 ; 

 Nov. 5, 1937, 2 $ . LaRue, McCann Spring: 



