34 
Thorax slaty gray, mesonotum with rather long and dense sil¬ 
very white pubescence, the three longitudinal lines more distinct 
than in the male, the lateral ones nearly straight, diverging pos¬ 
teriorly; scutellum with apex yellowish and sides often broadly 
margined with yellowish; metanotum about as in the male. 
Abdomen with a pale grayish median stripe, broadened basally 
and apically; pubescence silvery, not very sparse, short on the 
median stripe, and rather long and wavy each side of it. 
Coloration of legs and form of metatarsus almost exactly as 
in the male; tarsal claws bifid. 
Wings as in the male; halteres yellowish fuscous. 
Length, 2 x / 2 to 3 mm. (alcoholic specimens about 4 mm.) ; 
wing, about 3 mm. 
Described from numerous specimens taken along the margin of 
the Illinois river at Havana April 26, 1912. 
Examples in alcohol, from the same locality April 22, 1898, 
show the leg pattern very distinctly (Fig. 3), and also the follow¬ 
ing yellowish markings which are not evident in the pinned speci¬ 
mens. The palpi are yellowish basally; there is a small pale spot 
on the pleura beneath the humeral angle; and the metapleura and 
scutellum are mostly yellowish. The extended abdomen may be 
described as yellowish with broad slaty-gray transverse bands, one 
to a segment, the anterior and posterior margins of the segments 
yellowish. In the male, on segments 6 to 8, these bands are more 
or less interrupted‘at middle; the ends of the bands extend around 
on the sides of the ventral surface, the venter is yellowish with a 
median row of dark spots bearing blackish hairs, and the last seg¬ 
ment is yellowish dorsally, sometimes with a small dark mark 
each side. In the female the bands are present on all but the last 
three segments, each band interrupted at middle by a quadrate yel¬ 
lowish spot, behind which the posterior margin is narrowly slate- 
colored; and the venter is yellowish. 
The color-pattern of the legs is unique so far as the American 
species are concerned. 
Larva .—We have not bred johannseni * and its immature stages 
are consequently unknown. We have taken two species of these 
Fig. 5. Simuliumjohannseni , larva, dorsal view. X 8%. 
*Since bred by us from the larva here assigned to it.—S. A. F. 
