132 Intinois NaturAL History Survey BULLETIN 
low to white. Abdominal tergites 2-6 
brown, with anterior fourth of each tergite 
yellow, sternites faint gray-brown or smoky 
tan; apical tergites bright chestnut or choc- 
olate brown, sternites white, sometimes 
faintly stained with tan; genitalia, fig. 294, 
white; caudal filaments white. 
Known from Illinois, New York, Ontario, 
Pennsylvania, and Quebec. 
Illinois Records. — ELcin: Botanical 
Garden, April 25, 1941, Ross & Burks, 1 ; 
April 19, 1939, Burks & Riegel, 8 N; May 
9. 1939, Ross & Burks, 56, 52, 40 N; 
May 23, 1939, Burks & Riegel, 16 N. 
12. Baetis incertans McDunnough 
Baetis incertans McDunnough (1925a: 220). 
Ide (1937b:223) considers this species to 
be a synonym of vagans. It is quite closely 
related to vagans, differing only in that it is 
smaller, the length of the body being 4.5 
mm. and the length of the fore wing 5 mm.; 
abdominal tergites 2-6 are uniformly brown, 
and abdominal sternites 2-6 are white or 
faintly tinged with yellow. 
Known from Quebec. 
13. Baetis pallidulus McDunnough 
Bactis pallidula McDunnough (1924a:8). 
Live specimens of pallidulus can be recog- 
nized at once by the brilliant lemon-yellow 
and tan head and thorax; the bright yellow- 
orange of the compound eyes also is dis- 
tinctive. These colors, unfortunately, are 
quickly lost following death. Regardless of 
the method of preservation of specimens, all 
trace of the bright yellow coloration is soon 
lost. In alcohol, the eyes and thorax fade 
to a pale tan or deep cream color; dry speci- 
mens become light or dark tan. 
Mate.—Length of body 4-5 mm., of fore 
wing 5-6 mm. Head tan and yellow; each 
antenna with scape and pedicel orange-tan, 
flagellum yellow; compound eyes orange- 
yellow. Thorax yellow and tan; legs yel- 
low, with faint, brown shading at apex of 
each femur; wings hyaline, veins Sc and R, 
yellow at bases, seven to nine stigmatic cross- 
veins, partly anastomosed; marginal inter- 
calaries in second interspace short, fig. 287; 
hind wing broad, costal angulation well de- 
veloped, third longitudinal vein only one- 
fourth as long as wing, usually one marginal 
Vol. 26, Art. 1 
intercalary vein posterior to second longi- 
tudinal vein. Abdominal segments 2-6 light 
tan or yellow, black spiracular marks usu- 
ally present; apical tergites orange-brown 
or tan, sternites yellow, sometimes stained 
with tan or orange-brown; genitalia yellow, 
of the intercalaris type, a well-developed 
apicomesal tubercle on the first forceps seg- 
ment, the second segment frustate; caudal 
filaments white. 
Known from Illinois, Indiana, and On- 
tario. 
Illinois Records. — Atprince: May 14, 
1940, Mohr & Burks, 1¢. AppLe River 
CANYON STATE Park: June 6, 1940, Mohr 
& Burks, 18; July 12, 1938, Burks & 
Boesel, 1¢. Muwncte, Stony Creek: May 
24, 1914, 34; June 3, 1917, 19; June 8, 
1927, Frison & Glasgow, 1¢. Oakwoopn: 
May 24, 1926, T. H. Frison, 1¢. Rock- 
ForD: June 13, 1931, Frison & Mohr, 1 ¢. 
SERENA: Indian Creek, May 12-16, 1938, 
Ross & Burks, 2¢. 
14. Baetis ochris new species 
This species is similar to pallidulus in — 
being generally light in color, in having 
male genitalia of the intercalaris type, and 
in having three well-defined, longitudinal 
veins and a well-developed costal projection 
in the hind wing. The two differ in that 
ochris has the marginal intercalaries in the 
first three interspaces of the fore wing equal 
in length, while pallidulus has them unequal, 
with those in the second interspace shorter 
than those in the first and third interspaces; 
the apical segments of ochris are brown, of 
pallidulus yellow or tan; abdominal ter- 
gites 2-6 are white in ochris, yellow in 
pallidulus. 
Mate.—Length of body and of fore wing © 
each 4 mm. Head tan, shaded with light 
yellow-brown near compound eyes; antennae 
yellow-brown; eyes yellow-brown. Thorax 
yellow-brown; wings hyaline, stigmatic © 
crossveins 7 to 10 in number, partly anasto- — 
mosed, a strong crossvein usually present in 
second interspace below stigmatic area near — 
margin of wing; marginal intercalaries in 
first three interspaces nearly equal in length, — 
fig. 286; hind wing broad, with three longi- — 
tudinal veins and usually no marginal inter- 
calaries, sometimes a very short one present — 
between first and second veins; legs white. 
