May, 1953 
area, costal crossveins present but irregular 
and often broken, stigmatic crossveins slant- 
ing, irregular, sometimes partly anastomosed, 
8 to 12 in number; femur of each leg usually 
with faint brown shading extending from 
base to apex, on outer side. Abdomen with 
dark brown spots as in male, but dorsal, 
light brown shading faint or wanting; dor- 
sum usually with many minute, punctate, 
brown dots scattered over surface; sternum 
punctate, but brown dots few; caudal fila- 
ments as in male. 
NympH.—Length of body 8-9 mm. Head 
brown, with a white spot just dorsal to 
each antennal socket and on meson between 
sockets; each antenna as long as fore leg. 
Thorax brown, with minute, white mottling 
on mesonotum; legs uniformly light brown. 
Abdominal dorsum mostly brown, with 
small area at base and apex of lateral pro- 
jection of each segment white, a single 
median spot or two submedian, coalescing 
spots on each tergite, and a longitudinal, 
white stripe on either side of median spot 
on each of tergites 2-8; gills semihyaline, 
tracheae lavender-brown; each gill borne 
by segments | and 2 triple, gills of seg- 
ments 3-6 double, seventh gill single; caudal 
filaments each with a subapical, dark brown 
crossband. 
Known from Illinois, lowa, New York, 
and Wisconsin. 
Illinois Records.—Specimens, collected 
April 23 to November 3, are from Belle- 
ville, Brussels, Cairo, Chambersburg, Col- 
linsville, Grand Tower, Greenville, Havana, 
Herod (pool near Gibbons Creek), Jones- 
boro, Morris, Mount Carmel, Muncie, Oak- 
wood, Peoria, Pingree Grove, Quincy, Ran- 
toul, Rock Island, Rosiclare, Springfield, St. 
Jacob, St. Joseph, Sterling, Urbana, Wau- 
kegan, and Western Springs. 
2. Callibaetis ferrugineus (Walsh) 
Cloe ferruginea Walsh (1862:379). 
There is at present in the Museum of 
Comparative Zoology a single male speci- 
men, determined as of this species by Walsh, 
which was collected at Rock Island, Illinois, 
a year after the original description was 
published. Unfortunately, it is badly broken 
but, insofar as the characters can be seen 
on this fragmentary specimen, it is in agree- 
ment with the current concept of the species. 
The female was unknown to Walsh, but the 
Burks: THE Mayr ties oF ILLINOIS 117 
association of the correct female to be 
placed with the male has been arrived at 
through the rearing of adults of both sexes 
from lots of nymphs that almost certainly 
represented pure cultures of the species. 
Mare.—Length of body 7.0-8.5 mm., of 
fore wing 8.0-9.5 mm. Color extremely 
variable, ranging from almost completely 
light yellow, with a few minute, brown spots, 
to almost completely brown, with darker 
brown or black markings. Head brown, with 
face below antennae white; each antennal 
scape and pedicel white, with apexes brown, 
flagellum white at base, gray or tan distad; 
upper eyes tan, lower gray, each with a 
brown, longitudinal stripe. Thorax brown 
to yellow, with dark, punctate spots on 
pleura and venter; wings hyaline, three 
costal veins faintly yellow; marginal inter- 
calaries of outer margin of each fore wing 
usually double; legs white to yellow, femora 
often with dark red, punctate spots, all 
femora vaguely darkened at apexes, each 
fore tibia red-brown at apex. Abdomen 
varying from yellow to almost black; dark, 
punctate spots present over most of sur- 
face, a dark, longitudinal, median, dorsal 
stripe often present; genitalia and caudal 
filaments white. 
FEMALE.—Length of body 8-9 mm., of 
fore wing 9-10 mm. Body invariably darker 
than that of male, varying from tan to 
almost black. Head usually grayish tan or 
brown, face below antennal sockets white to 
tan, eyes gray, with brown band. Thorax 
usually dull gray-brown on dorsum; wings 
hyaline, each typically with dark brown 
shading occupying entire anterior three in- 
terspaces and usually extending posteriorly 
onto R, sometimes reaching almost to vein 
M, fig. 222; veins often alternately brown 
and white and outer margin of wing often 
spotted with brown; hind wing usually 
brown at base; legs yellow to tan or light 
brown; all femora always with broad, dark- 
ened areas at apexes. Abdomen usually dark 
brown to almost black; caudal filaments 
white, occasionally with some basal articu- 
lations darkened. 
NympH.—Fig. 266. Length of body 8-9 
mm. Head brown, with a white spot just 
dorsal to each antennal socket, on either gena 
just ventral to each compound eye, and on 
meson between antennal sockets; each an- 
tenna slightly longer than fore leg. Thorax 
brown, slightly mottled with darker brown 
