May, 1953 
Burks: THE Mayr.ies or ILLINoIs 4] 
Fig. 79.—Hexagenia rigida, claw of middle 
leg of mature nymph. 
Fig. 80.—Hexagenia bilineata, claw of mid- 
dle leg of mature nymph. 
Fig. 81.—Hexagenia munda, claw of middle 
leg of mature nymph. 
Fig. 82.—Hexagenia bilineata, hind wing 
of female. 
Fig. 83.—Hexagenia atrocaudata, hind wing 
of female. 
Fig. 84.—Hexagenia limbata, dark phase, 
hind wing of female. 
Fig. 85—Hexagenia limbata, 
hind wing of female. 
Fig. 86.—Hexagenia 
hind wing of female. 
light phase, 
rigida, dark phase, 
Fig. 87.—Hexagenia rigida, light phase, hind wing of female. 
Freeport, Giant City State Park, Gilman, 
Glen Ellyn, Grayslake, Havana, Homer, 
Kankakee, Kickapoo State Park, Laclede, 
La Salle, McHenry, Mahomet, Momence, 
Monticello, Morris, Mount Carmel, Mur- 
physboro, New Milford, Oakwood, Oregon, 
Peoria, Poplar Bluff, Quincy, Rantoul, 
Richmond, Rockford, Rock Island, Rood- 
house, Rosecrans, Springfield, Spring Grove, 
Urbana, and Waukegan. 
4. Hexagenia munda Eaton 
Hexagenia munda Eaton (1883: 53). 
Hexagenia affiliata McDunnough (1927c: 119). 
Hexagenia carolina Traver (1931b:601, 616). 
Hexagenia elegans Traver (1931: 594). 
Hexagenia marilandica Traver (1931b:599). 
Hexagenia orlando Traver (1931b:608). 
Hexagenia rosacea TVraver (1931b:607). 
Hexagenia weewa Traver (1931b:605). 
Hexagenia kanuga Traver (1937:29). 
This species is distinguishable from Jim- 
bata only in the male and the nymph. Male 
genitalia, fig. 76, have penis lobes in form 
of elongate, shallow hooks. Nymph has a 
relatively narrow, straight-margined fron- 
tal process, fig. 71; mid-tarsal claw slender 
near tip, fig. 81. 
Known from the northeastern, central, 
and southeastern states; it is extremely rare 
in Illinois, possibly an adventive. Apparently 
normally develops in small lakes. 
Illinois Record.—Monticello: April 11, 
1934, 1¢. 
5. Hexagenia rigida McDunnough 
Hexagenia bilineata falcata Needham 
(1921: 292; pl. 81, fig. 65). 
Hexagenia rigida McDunnough (19245:90). 
Mave.—Length of body 18-24 mm., of 
fore wing 16-20 mm. Eyes separated on 
meson by a space equal to diameter of one 
eye. Thorax mostly dark red-brown; fore 
wing hyaline, costal interspace stained with 
brown, veins and crossveins dark brown; 
hind wing with prominent discal spots, 
outer margin usually with brown band. 
Abdomen with extensive, dark red-brown 
color pattern on yellow- or red-brown back- 
ground; penis lobes, fig. 74, elongate, almost 
straight. 
FEMALE.—Length of body 18-28 mm., 
of fore wing 18-24 mm. Background color 
of body white or light cream; dorsal ab- 
dominal pattern dull red, venter entirely 
