68 
evidently a synonym of meridionale Riley; decorum Walk. of vittatum 
Zett.; and molestum Harris equals venustum Say. 
In several species the color of the femora varies from yellow with 
brown tips to wholly brown. The knob of the halteres is always yel- 
low. In the female the abdomen consists of eight segments, but there 
is an additional one in the male. Illustrations 
of the female of invenustum, and of the male of 
meridionale are reproduced in figures 16 and 17. 
With the exception of argus Williston, which 
is unknown to the writer, the following table 
contains all the species known to occur in the 
United States, all of which are represented by 
both sexes in the National Museum collection. 
TABLE OF THE SPECIES OF SIMULIUM. 
1. Thorax largely or wholly blackish. .............. 2 
Thorax and entire insect yellow, the head, abdo- 
‘ . men, and tarsi sometimes blackish; length, 3™™, 
e BO Custer Co., Colo., and Bear Paw Mts., Mont. 
Fia. 16.—Simulium invenustum: ochraceum Walk. 
female fly, enlarged (after 
Riley; Rept. Dept. Agr. 1886). 
2. Hind tarsi distinctly bicolorous, yellowish and 
blackish: s..2 2 cece Sood ass eee ace oe ee 4 
Hind and other tarsi and all legs unicolorous, yellow, brown, or black.....-.. 3 
8. Abdomen of female gray, marked with a velvet-black fascia on segments 3 and 4, 
and sometimes with two subdorsal spots of the same color on 2, 5, and 6; 
thorax bluish gray, with three black vittw; mesonotum of male velvet black, 
unmarked; the dorsum of abdomen of the same color, marked with a gray 
spot on sides of segments 3, 6, 7, and 8; length, 1.5 to 2™™, Boston, Mass. ; 
Agricultural College, Mississippi; Texas and Nebraska-.-..- meridionale Riley. 
Abdomen of female grayish brown or black, the sides marked with a row of vel- 
vet-black spots; mesonotum grayish brown, marked with three darker vitt; 
mesonotum and abdomen of male grayish brown, 
unmarked; length, 2 to 5™™. White Mountains, 
New Hampshire; Catskill Mountains, New York 
(May); Adirondack Mountains, New York (May); 
Wilmuth, N. Y.; Cambridge, Mass.; Roxbury, 
Conn.; District of Columbia; Grand Ledge, Mich. ; 
Lakeview, Miss., and Louisiana.. invenustum Walk. 
4. Eyes widely separated (females) ...-.---.--.-.------ 5 
Eyes contiguous (males) eye--- ase hee 9 
5. Sixth, and usually the two succeeding segments of 
abdomen opaque, the sixth marked with velvet 
black |. 2s. s ised ee sete ees ee es ee 6 Fie. 17.—Simulium meridio- 
Sixth and two succeeding segments of abdomen sub. 7#le: male fly, enlarged 
shining brown and destitute of velvet-black mark- _(fter_Riley; Rept. Dept. 
c Agr., 1886). 
ings, segments 3, 4, and 5 opaque velvet black; meso- 
notum grayish black, not vittate, the sides and front corners light gray; bases 
of tibie usually, of first joint of the middle and hind tarsi, and sometimes 
bases of femora, yellow; front side of front tibiw metallic silvery; length, 1.8 
to 3™™, Beaver Mine, Canada; Franconia and White Mountains, New Hamp- 
shire; Lake Placid, New York; Huron Mountains, Michigan; Minnesota; 
National Park, Wyoming; Glenora, British Columbia; Wilsons Peak, Cal.; 
Texas; Louisiana; Lakeview, Miss., aud Biscayne Bay, Fla.... venustwm Say. 
