| 
ee eee 
May, 1953 
caudal filaments with alternating brown and 
white banding. 
Known from New York, North Carolina, 
Ohio, Pennsylvania, Virginia, and West 
Virginia. 
5. Heptagenia patoka Burks 
Heptagenia patoka Burks (1946:612). 
Mare.—Length of body and of fore wing 
9 mm. Head tan; compound eyes sepa- 
rated on meson by a space as wide as lateral 
ocellus. Thorax brown, pleura yellow; each 
fore leg light tan, fore femur with red- 
brown shading in middle and at apex, brown 
shading at apex of fore tibia and at articu- 
lations of tarsus, first fore tarsal segment 
one-third as long as second; wings hyaline, 
veins and crossveins brown, with crossveins 
in costal and subcostal interspaces of fore 
wing broader and darker than others. Ab- 
domen red-brown on dorsum, light yellow- 
ish tan on venter; tergites 1-3 each with a 
pair of yellow, submesal, round spots near 
anterior margin, following tergites with 
these spots more elongate and progressively 
darker and more vague, becoming scarcely 
distinguishable from dark ground color; a 
faint, median, yellow line present on tergites 
1-5; sternites unmarked; apical three seg- 
ments shaded with tan; genitalia, fig. 367, 
tan, with brown shading at edges; caudal 
filaments tan, articulations brown. 
NympH.—Unknown. 
The species is known only from Illinois. 
Illinois Record.—PatToKa: July 19, 1945, 
Ross & Sanderson, 1 ¢. 
6. Heptagenia flavescens (Walsh) 
Palingenia flavescens Walsh (1862:373). 
Mace.—Length of body 8-11 mm., of 
fore wing 10-13 mm. Head yellow, vertex 
shaded with tan; compound eyes grayish 
yellow-green, the two eyes separated on 
meson by a space slightly wider than a lat- 
eral ocellus. Thorax mostly red-tan, with 
pleura mostly yellow. Legs yellow, each 
fore femur shaded with red-brown in middle 
and at apex, fore tibia and tarsal segments 
shaded with gray-brown at apexes, first tar- 
sal segment one-fifth as long as second seg- 
ment; middle and hind femora shaded with 
brown at apexes; wings hyaline, veins and 
crossveins brown, those of hind wing 
slightly lighter brown, basal costal cross- 
Burks: THE MAYFLIES OF ILLINOIS 
187 
veins of fore wing weak or virtually want- 
ing. Abdomen yellow, with a broad, median, 
gray-brown band on tergites 1-7, a narrow, 
dark gray, transverse band at posterior mar- 
gin of tergites 1-7 or —8; apical three ter- 
gites orange-tan, apical two sternites shaded 
with orange-tan; genitalia, fig. 368, with 
forceps tan or yellow and penis lobes rose- 
pink; caudal filaments white or pale yellow, 
articulations brown or tan. 
FEMALE.—Length of body 9-12 mm., of 
fore wing 11-15 mm. Head and _ thorax 
entirely yellow, or mesonotum faintly stained 
with tan; legs as in male; abdomen yellow, 
without dark, dorsal shading or with me- 
dian, dorsal area faintly tan stained, a 
narrow, transverse, gray line present at 
posterior margins of tergites 1-8 or —9; ter- 
minal abdominal sternite more deeply cleft 
on meson of posterior margin than in dia- 
basia; caudal filaments white. 
Nympu.—Fig. 384. Length of body 12-16 
mm. Head mostly dark brown, with a prom- 
inent, triangular, white mark extending 
from anterolateral angle of each compound 
eye to lateral margin of head. Thorax 
brown, with small, irregular, white spots, 
each tarsal claw with a prominent basal 
tooth, but no ventral denticles. Abdomen 
dorsally dark brown with, typically, a pair 
of submedian, a pair of sublateral, and a 
pair of anterolateral, white spots on each of © 
tergites 2-7; tergite 1 mostly white; sub- 
median spots of tergite 4 and of 5 enlarged 
so as to coalesce at posterior margin; ter- 
gites 8 and 9 each white in median area, 
brown laterally; tergite 10 usually entirely 
brown; gills borne by seventh segment with 
well-developed ventral tuft of filaments; en- 
tire venter white, except that posterior mar- 
gin of sternite 9 has a brown border; caudal 
filaments alternately banded brown and 
white. 
Known from Georgia, Iowa, Illinois, 
Kansas, Manitoba, Minnesota, and Texas. 
Illinois Records.—BILietr: May 6, 1942, 
Burks & Mohr, 29. Carvin: May 26, 
1942, Mohr & Burks, 1¢. Drxon: June 
27, 1935, DeLong & Ross, 1¢. FREEPORT: 
June 10, 1948, Burks & Stannard, 1¢. 
Havana: May 18, 1894, Hart, 1¢. Mount 
CarRMEL: April 22, 1946, Mohr & Burks, 
26 uli ae Onncom 7: July <9,! 1925; “A 
Frison, 14¢, 172; July 13, 1926, Frison 
& Hayes, 26; July 19, 1927, Frison & 
Glasgow, 3¢. PropHETSTOWN: July 19, 
