August, 1944 



Ross: Caddis Flies of Illinois 



171 



areas. There is only a single generation per 

 year, the adults being present in June and 

 early July. 



Illinois Records. — Algonquin: June 

 30, 1906, 1 9 ; May 25, 1908, 1 ? ; July 9, 

 1909, 1 9 ; July 12, 1910, 1 9 , all by W. A. 

 Nason. Cedar Lake: June 19, 1892, H. S. 

 Shiga, 19. Champaign: at electric light, 

 June 17, 1886, Hart, 1^. ZiON : many 

 larvae, pupae and adults (including the type 

 series) taken in or near Dead River from 

 May 15 to July 7. 



Ptilostotnis Kolenati 



Ptilostomis Kolenati (1859^, p. 198). Geno- 

 type, monobasic: Ptilostomis kovalevskii Kole- 

 nati. 



All the species of this genus are brown, 

 frequently with an angulate dark brown 

 mark in the hind wings. The shelflike 

 projection of the male ninth sternite and 

 the broad ninth sternite of the female, with 

 its two lateral finger-like processes and 

 mesal triangular process, are diagnostic. 

 The larvae have no mesal dark line down 

 the frons and have the diagonal marks on 

 the pronotum forming an arcuate mark, fig. 

 565. To date no characters have been found 

 to separate the larvae to species. They make 



a long cylindrical case of spiral formation 

 similar to that of other members of the 

 family. 



Four species of the genus are recognized, 

 three of which occur in Illinois. The geno- 

 type, kovalevskii, described from Alaska, has 

 never been identified definitely, and we do 

 not know whether it constitutes a fifth Ne- 

 arctic species of the genus or whether it is 

 the same as one of the four treated below. 



KEY TO SPECIES 

 Adults 



1. Maxillary palpi 4-segmented (males) 2 

 Maxillary palpi 5-segmented (females) 5 



2. Apex of tenth tergite with a pair of 



long, curved, filiform blades, fig. 



594 semifasciata, p. 173 



Apex of tenth tergite at most with 

 long setae, fig. 595 3 



3. Base of tenth tergite with two pairs of 



processes which arise from it, then 

 angle suddenly and run parallel 

 with the segment; the dorsal pair is 

 very long, the lateral pair short, fig. 



595 postica, p. 1 73 



Base of tenth tergite at most with a 

 lateral pair of processes, figs. 596, 

 597 4 



4. Tenth tergite flat and rectangular, with 



596 

 A 



OCELLIFERA 



ANGUSTIPENNIS 



Figs. 594-597. — Ptilostomis, male genitalia. A, lateral aspect; B, tenth tergite, dorsal 



aspect. 



