August, 1944 



Ross: Caddis Flies of Illinois 



123 



U , 6 $ . Richmond: June 20, 1938, Burks 

 & Boesel, 5$. Savanna: July 10, 1927, 

 Frison & Glasgow, at light, 1 9 . Spring 

 Grove: Fish Hatchery, May 10, 1935, 

 Frison & Ross, 1$ , 1 $ ; June 9, 1938, 

 Burks & Mohr, 5^, 5$ ; June 17, 1938, 

 at light, Burks & Boesel, 1 9 ; Nippersink 

 Creek, June 17, 1938, B. D. Burks, 2 9 ; 

 Fish Hatchery, July 11, 1938, Burks & 

 Riegel, 4 larvae. 



Ithytrichia Eaton 



Ithytrichia Eaton (1873, p. 139). Genotype, 

 monobasic: Ithytrichia lamellaris Eaton. 



The curious hydroptilid larva described 

 by Needham (1902) is probably of this 

 genus. At the time Needham considered 

 the larva (prepupa) with lateral append- 

 ages, fig. 456, to be a different phase of 



Fig. 456. — Ithytrichia? larva. (After Needham.) 



another larva without such appendages but 

 collected with it. I have observed no such 

 phenomenon in prepupae of other Hydrop- 

 tilidae. Furthermore the larva under dis- 

 cussion fits descriptions of a European spe- 

 cies of this genus (Morton 1888). I be- 

 lieve that two genera were involved in Need- 

 ham's collecting. His larva without the 

 lateral appendages (1902, fig. 1) may have 

 been a species of Oxyethira ; the one with 

 lateral appendages (1902, figs. 2-5) was 

 probably Ithytrichia clavata. Both were in 

 cases apparently resembling fig. 465. 



Both Nearctic species have been taken in 

 Illinois. The female of one of these is un- 

 known. The adults have the salt-and-pep- 

 per markings typical of many Hydroptilidae. 



KEY TO SPECIES 



Males 



1. Claspers with ventral aspect nar- 

 rowed to a slender apex; side plates 

 of ninth segment with apex narrow, 

 lateral aspect downcurved, ventral 



aspect flared, fig. 457 



clavata, p. 124 



Figs. 457-458. — Ithytrichia, male genitalia. 

 /}, ventral aspect; B, lateral aspect; C, aedea- 

 gus. 



Claspers with ventral aspect parallel 

 sided, apex wide and truncate; side 

 plates of ninth segment with apex 

 wide, without flared end, fig. 458. . . 

 mazon, p. 1 24 



