104 MISC. PUBLICATION 305, U. S. DEPT. OF AGRICULTURE 
Abdomen above dark orange brown, with a median black stripe, which often 
widens apically; in this dark stripe a row of small, but usually distinct, whitish 
triangles ; posterior margins of tergites laterally with white hair; considerable 
variation in the extent of the black, in some consisting of a very narrow stripe 
and in others covering most of the abdomen; venter reddish, with a distinct, 
broad, median stripe of dark brown; hind margins of sternites with a thin 
white fringe. 
Male-—tEye with areas of large and small facets sharply differentiated, the 
small facets extending around margin of eye to vertex; upper surface of eye 
somewhat flattened. Second palpal segment about twice as long as greatest 
width, blunt at apex, pale reddish, with black and white hair. Mesonotum 
with long grayish hair. Hind tibial fringe a mixture of black end white. 
Rest of coloration much as in female. 
FIGURE 47.—Antenna, front view of head, and palpus of (4) Tabanus actaeon and (B) 
T. lacustris. 
Type.—One of the four cotype females now in the Museum of 
Comparative Zoology, No. 4036, labelled and herein designated as 
lectotype. 
Type locality—Massachusetts. 
Distribution —Minnesota to Nova Scotia and south in Atlantic 
States to North Carolina. July 25 (Melrose Highlands, Mass.) to 
September 23 (Mount Holyoke Gap, Mass.). In the United States 
National Museum, 18 females, 1 male. 
This species resembles catenatus Walker, but, in addition to the 
characters mentioned in the key, actaeon is somewhat smaller, the 
abdomen has more black, the white triangles are somewhat broader 
at base, and the hind tibia is considerably paler. In the male the 
genae are pale grayish in actacon, yellowish in catenatus, 
TABANUS LACUSTRIS Stone 
(Fig. 47, B) 
Tabanus lacustris Stone, Ent. Soc. Wash. Proc. 37: 18-14, 1935. 
Medium sized; dark brown, with a median row of prominent gray triangles 
on abdomen; fore tibia bicolored; a stump vein and infuscated spot at furca- 
tion; cell R; closed or very much narrowed. 
Female—Length 16-19 mm. Eye bare. Frons yellowish gray, with dark 
streaks to each side of median callus and with short black hair, five and 
one-half to six times as high as width at basal callus and slightly widened 
above; basal callus dark reddish brown, narrowly separated from eyes and 
distinctly higher than wide; median callus a slender connected line of same 
color; subeallus flat, yellowish gray. Antenna nearly or quite black, with 
black hair; first segment considerably widened apically; second with strong 
dorsal process; third with basal portion about two-thirds as broad as long, 
the dorsal angle prominent and dorsal excision deep; annulate portion slender, 
slightly shorter than width of basal portion. Clypeus and genae gray, with 
white hair. Second palpal segment moderately enlarged at base and distinctly 
tapering apically, yellowish white, with short, mostly black hair. 
