May, 1953 
pellicle during flight; it is quite possible that 
all species of the genus do likewise. 
The first-described Nearctic species in 
this genus, allectus (Needham) (1905: 47), 
is now virtually unidentifiable. It cannot 
be placed from the characters given in the 
original description alone. ‘The types are, 
furthermore, either lost, or represented by 
only a few fragments. These fragments of 
specimens are not certainly the types, but 
might be; in any event, they are not in good 
enough condition to serve as a basis for an 
identification of the species. 
Reliable characteristics for the separation 
to species of females and nymphs of this 
genus have not yet been found. 
KEY TO SPECIES 
Aputr Mates 
1. Wings with all crossveins hyaline; an- 
tennal scape black...... 1. stygiatus 
Wings with anterior crossveins brown; 
antennal scape white or yellow, tinged 
WitMFEG=DEOWNE 62) yo sie cee es <a 2 
Vertex of head black........ 2. atratus 
Vertex of head mostly light yellow...... 
oeeh aie OL cee eee 3. peridius 
in) 
1. Tricorythodes stygiatus McDunnough 
Tricorythodes stygiatus McDunnough 
(1931¢:267). 
Mare.—Length of body 2.5-3.0 mm., 
of fore wing 3.5-4.0 mm. Head black, com- 
pound eyes and ocelli black; each antennal 
scape black, pedicel tan, flagellum yellow. 
Pronotum black, mesonotum very dark 
brown, metanotum yellow-brown; meso- 
and metapleura dark red-brown, with 
vague, black markings near wing bases; 
thoracic sternum dark red-brown; all 
coxae black; femora black, with red shading 
and with vague, longitudinal, yellow streaks; 
tibiae white, mottled with black and red- 
brown over basal three-fourths; tarsi white 
or gray; wings hyaline, anterior longitudinal 
veins brown. Abdominal tergum_ black; 
tergites 3-7 lighter near lateral margins: 
sternites dull yellow, suffused with gray, and 
with a median, black mark at posterior 
margin of each sternite; caudal filaments 
white, shaded with gray near bases. Geni- 
talia, fig. 101, yellow to white, with penis 
lobes relatively narrow and median inden- 
tation at posterior margin of forceps base 
relatively narrow and shallow. 
Burks: THE Mayrties or ILiinors 47 
Known from Illinois, Michigan, New 
Brunswick, and Quebec. Develops in almost 
stagnant eddies along large streams. 
Illinois Record—Wi_mincron: at light, 
Aug. 6, 1947, Burks & Sanderson, 42. 
2. Tricorythodes atratus (McDunnough) 
Tricorythus atrata McDunnough (1923:39). 
It is quite possible, as McDunnough 
(193le:265) has said, that atratus is the 
same as allectus (Needham 1905:47), al- 
though the characters given in the original 
descriptions are not quite identical. As was 
remarked above, the specimens at present 
taken for the types of allectus are not in 
good enough condition to serve as a basis 
for an identification of the species. It is 
preferable at present to use atratus for the 
species, as that name is based on a detailed 
description, and the types are well preserved 
and available for study. 
Mave.—Length of body 3.0-3.5 mm., of 
fore wing 3.5-4.5 mm. Head black, com- 
pound eyes black, each antenna yellow or 
white, with faint, gray shading at base of 
pedicel. Pronotum black, becoming brown 
at lateral margins; mesonotum and metano- 
tum dark brown, pleura lighter brown, 
sternum dark brown; coxae and trochanters 
dark gray; femora gray, with black shading, 
subapical area of each with red-brown shad- 
ing; fore tibia brown, with median, black 
shading, middle and hind tibiae white, with 
black shading in middle, fore tarsus gray; 
middle and hind tarsi white; wings hyaline, 
veins Sc and R, shaded with gray, anterior 
veins and crossveins brown. Abdomen yel- 
low-gray or white; tergites 1 and 2 com- 
pletely shaded with black, tergites 3—7 black 
only on meson and at posterolateral angles, 
apical tergites covered by black shading; 
sternites yellowish gray, with a median, 
black mark at posterior margin of each 
sternite; caudal filaments white, shaded with 
gray near bases. Genitalia, fig. 100, white 
or light yellow, with penis lobes relatively 
wide and apical, median excavation of for- 
ceps base relatively wide and deep. 
Known from Illinois, Michigan, and 
Quebec. Develops in almost stagnant eddies 
of larger streams. 
Illinois Records.—MILan: Rock River, 
June 4, 1940, Mohr & Burks, 1 6. Orecon: 
at light, July 18, 1927, Frison & Glasgow, 
