72 



Illinois Natural History Survey Bulletin 



Vol. 23, Art. 1 



meson and reach beyond sternite ; ninth seg- 

 ment long and somewhat vasiform, without 

 conspicuous internal processes. 



Taken in all parts of the state, this spe- 

 cies shows a marked preference for large 

 rivers such as the Illinois, Kaskaskia and 

 Mississippi; however, we have taken it in 

 numbers along many small streams. Usual- 

 ly it is taken in only small numbers, but 

 occasionally large swarms are encountered. 

 The adult emergence occurs from May until 

 October. 



The species is widely distributed through 

 the central states; records include Alabama, 

 Arkansas, Illinois, Kentucky, Michigan, 

 Minnesota, Missouri, Ohio, Oklahoma, 

 Tennessee and Wisconsin. It is also known 

 from near the mouth of the Amazon River 

 in South America. 



Illinois Records. — Many males and fe- 

 males, taken May 29 to October 10, are 

 from Algonquin, Antioch, Bartonville (Kick- 

 apoo Creek), Danville, Deer Grove (Green 

 River), Dixon, East Dubuque, Elgin (Bo- 

 tanical Gardens), Grafton, Hamilton, Har- 

 din, Havana (Spoon River), Herod, Kan- 

 kakee (Kankakee River), Milan (Rock 

 River), Olive Branch (Horse Shoe Lake), 

 Ottawa, Palos Park (Mud Lake), Pontiac, 

 Ripley (La Moine River), Rockford, Rock 

 Island, Springfield (Sangamon River), 

 Spring Grove, Thebes, Venedy Station 

 (Kaskaskia River). 



C ernotina Ross 



Cernotina Ross (1938fl, p. 136). Genotype, 

 by original designation: Cernotina calcea Ross. 



No larva of this genus has been discov- 

 ered. The adults of both sexes are 5-6 mm. 

 long, with the head, body and appendages 

 straw color, the wings and parts of the legs 

 darkened with brown hair. The female geni- 

 talia are similar in all species known, the 

 genital segments forming a conical structure 

 with only simple parts, fig. 267. 



Fig. 267. — Cernotina calcea, female genitalia. 



Of the six North American species, only 

 one has been taken in Illinois, but three 

 others are known from Michigan and Ohio 

 and may eventually be found in the state. 



KEY TO SPECIES 

 Males 



1. Cerci with 3 or 4 long, black teeth on 



mesal side near base, fig. 268 



calcea, p. 72 



Cerci without long, black mesal teeth 2 



2. Apex of cerci long and ribbon-like, the 



inner margin just beyond apex set 

 with a row of 5 to 7 small teeth, fig. 



269 pallida, p. 73 



Apex of cerci shorter and whiplike, the 

 inner margin without teeth, fig. 270 3 



3. Base of clasper with a sclerotized, 



ovoid plate attached underneath it, 



fig. 270 spicata, p. 73 



Base of clasper without this plate, 

 fig. 271 Ohio, p. 73 



Cernotina calcea Ross 



Cernotina calcea Ross (1938fl, p. 137); cf, 9. 



Adults. — Length 5-6 mm. Head and 

 body straw color, typical for genus. Male 

 genitalia, fig. 268: tenth tergite merging 

 with ninth, the resulting structure with a 

 deep, V-shaped incision on meson; cerci with 

 three to four large, black mesal teeth near 

 middle, the apex lengthened into a long, 

 slender sinuate rod; claspers stocky, the 

 apex formed into a clawlike structure, and 

 the dorsal margin with a slender arm at 

 middle; aedeagus tubular and only slightly 

 sclerotized. Female genitalia, fig. 267, coni- 

 cal, without heavily sclerotized internal 

 parts or supports. 



Our only Illinois records are from Kan- 

 kakee and Oakwood. The species is always 

 found along clear, cool streams. Adult 

 emergence extends over a considerable peri- 

 od; our Illinois records indicate a span 

 from June 29 to August 1. 



The range of the species is incompletely 

 known. It is apparently quite widely but 

 locally distributed in cooler streams as indi- 

 cated by records from Illinois, Florida, Mis- 

 souri, Oklahoma and Texas. 



Illinois Records. — Kankakee: Aug. 1, 

 1933, Ross & Mohr, 1 5 ; July 21, 1935, 

 Ross & Mohr, 1 5 ; June 29, 1939, Burks 

 & Ayars, 25. Oakwood: July 18, 1933, 

 Ross & Mohr, 1 5 . 



