266 



Illinois Natural History Survey Bulletin 



Vol. 23, Art. 1 



two species of Brachycentrus adults. At the 

 time of spring emergence, the river is always 

 in flood, so that we have been able to obtain 

 pupae of only nurnerosus, which frequents 

 shallower water than does lateralis. 



Little is known regarding the range of 

 the species. Records are available for Illi- 

 nois, Kentucky and Michigan. 



Illinois Records. — Chicago: \S, fm. 

 Momence: May 4, 1937, Ross & Mohr, 

 2 3; May 17, 1937, Ross & Burks, 3$, 

 9 9 ; June 12, 1938, Ross & Burks, 1 larva; 

 Kankakee River, May 7, 1940, B. D. Burks, 

 5^,2$; May 1, 1941, T. H. Prison, 2 $ . 



Brachycentrus americanus (Banks) 



Oligoplectrum americanum Banks (1899, p. 

 210); c^. 



Brachycentrus similis Banks (1907«, p. 124); 



Not as yet taken in Illinois. The species 

 is extremely widespread through the north- 

 ern part of the continent from coast to coast, 

 with records from Alberta, California, Col- 

 orado, Michigan, Utah, Vermont, Wiscon- 

 sin and Wyoming. Collections from Wis- 

 consin are of peculiar interest because of 

 the case-building habits of the larvae. Here 

 we have found cases which were perfectly 

 round in cross section rather than square, 

 these round cases mingled with square ones, 

 and frequently with cases which were round 

 at the bottom and square at the top. Ap- 

 parently the larva is quite as well able to 

 make a circular case from its own secretion 

 as to build the square case considered typi- 

 cal for the genus. 



not of generic value; therefore I am consid- 

 ering the two names just mentioned as 

 synonyms of Sericostoma. 



HELICOPSYCHIDAE 



The familiar snail case represents the 

 only genus in this family, Helicopsyche. 

 Various authors have commented upon the 

 distinct features of this group, and Betten 

 in particular (1934, p. 414) has given a very 

 clear summary of the oddity of its charac- 

 ters. On the basis of the curious structures 

 of both larvae and adults, it seems best to 

 consider this as a distinct family, 



Helicopsyche Hagen 



Helicopsyche Hagen (1866, p. 252). Geno- 

 type, monobasic: Notidobia horealis Hagen. 



Distinctive of the larva are the following 

 characters: anal legs with a comb; head 

 with frons wide, running close to eyes, with 

 a ridge running from dorsal margin of eye 

 to above mandible, antennae short, situated 

 under this ridge and midway between eye 

 and mandible; legs of medium length; pro- 

 notum long, mesonotum forming a large 

 erect shield and divided into parts by pale 

 areas as in fig. 905. Pupae have the anal 

 appendages as in fig. 49. The adults are 

 readily distinguished by the short mesoscu- 

 tellum, with its narrow transverse wart, 

 and the hamuli on the hind wings. 



Four species are known from the United 

 States, only one of which has been taken 

 in Illinois. A key which will separate it 

 from its allies is given on p. 288. 



SERIGOSTOMATIDAE 



In North America this family contains 

 only the genus Sericostoma. The Nearctic 

 species have generally been placed in Noti- 

 dobia by previous American authors. There 

 are no Illinois representatives of this fam- 

 ily, the species being restricted to the moun- 

 tainous regions of the East and West. No 

 Nearctic species have been reared. 



As with the genus Lepidostoma, the genus 

 Sericostoma has been divided into several 

 genera, such as Notidobia and Schizopelex, 

 almost entirely on the basis of the secondary 

 sexual characters of the male. The uni- 

 formity of general characteristics in the fe- 

 males indicates that these differences are 



Helicopsyche borealis Hagen 



Notidobia borealis Hagen (1861, p. 271); d". 



Helicopsyche calif ornica Banks (1899, p. 

 210); cf. New synonymy. 



Helicopsyche annulicornis Banks (1904^, p. 

 212); d^. 



Larva. — Fig. 905. Length 8 mm. Head 

 and thoracic sclerites brown, legs straw 

 colored. Head, thoracic sclerites and legs 

 with abundant long hair. 



Case. — Fig. 906. Built in the form of a 

 spiral coil, its diameter about 5 mm., shaped 

 like a snail shell, made of sand grains and 

 small stones. 



Adults. — Length 5-7 liim. Head, body 

 and appendages straw colored, the body and 



