14 Myron Harmon Swenk 
Tyre LocaLiry.—Carlinville, Illinois; types in collection of 
Mr. Charles Robertson. 
Mr. Robertson originally described this species from a single 
male specimen captured at Carlinville, and three years later de- 
scribed the female from five specimens taken in the same local- 
ity. He gives its season as May 29 to June 29 and says it is an 
oligotropic visitor of Specularia perfoliata. In Nebraska, how- 
ever, it visits also the closely allied Campanula rotundifolia, while 
I have a female taken on Melilotus alba, In Texas it occurs on 
Callirhoe involucrata and Asclepias latifolia, while the types of 
opuntiae were taken on Opuntia and Campanula. In Nebraska 
it is commonest in Sioux county and along the northern border 
of the state, where it flies from June 16 to July 16, but mostly in 
late June. In Texas it flies from March 28 to June 7, while my 
Montana example was captured August 7. Apparently, then, it 
is principally a summer species which varies its season consider- 
ably according to the latitude and altitude. It is found over most 
of the eastern United States between the Atlantic coast and the 
crest of the Rocky mountains, my records showing it to range 
from New Jersey (North Woodbury) west to western Montana 
(Missoula), central Colorado (Boulder), eastern Oklahoma 
(Ardmore) and Texas (Fedor, Dallas). Probably it is not a 
very common species anywhere. C. opuntiae Ckll., said to differ 
from brevicornis g by darker nervures, dark apical tarsal joints 
and darker mandibles, represents merely one end of the individual 
variation of the species, similar specimens occurring anywhere 
in its range; hence I have here regarded the two as quite 
identical. 
SPECIMENS EXAMINED—Indiana: Elkhart, 3; Montana: Mis- 
soula, 1; Nebraska: Warbonnet Canyon, Sioux county, 5; Spring- 
view, 6; Carns, 2; New Jersey: North Woodbury, 1; Oklahoma: 
Ardmore, 1; Texas: Fedor, 13; Dallas, 4. 
Colletes willistoni Robertson. 
1891. Colletes Willistoni Robertson, Transactions of the American En- 
tomological Society, xviii, pp. 60-61, 2 (April, 1891); original 
description. 
56 
