20 BULLETIN OF WISCONSIN NATURAL HISTORY SOCIETY. VOL. 4, NOS. 1-2. 
apparatus. Otherwise the flowers of both species agree very 
closely. Proterandrv to such an extent as it exists in both of 
them makes cross-pollination the only probable outcome. 
I have taken the following insects on the flowers of Pamassia 
Caroliniana : 
A. IIYMENOPTERA. 
Apidse: (i) Apis mcllifcra L. worker, s. ; (2) Bombus aflinis, 
Cr. worker, s. ; Andrenidae: (3) Andrcna parnassicB CklL, female, 
s. and c. p. ; (4) Hal ictus zephyrus Sm. female, s. and c. p. ; 
Jchneumonidse : (5) Lampronota frigida, Cr. s. ; (6) L. anicricona 
Cr., s. 
B. DIPT ERA. 
Bombyliidae: (7) Anthrax alternata Say; Syrphidae: (8) 
Paragus bicolor Fabr. ; (9) Melanostoma mcUinum L. ; (10) 
Syrphus amcricanus Wied ;. (it) AUograpta obliqua Say; (12) 
Mesogramma polita Say; (13) Scricomyia chrysotoxoides 
Meig. : (14) Eristalis tcnax L. ; (15) E. dimidiatus Wied.; 
(16) Hclophilus similis Macq. ; (17) Syritta pipiens L. ; Tachi 
nidae: (18) Exorista nigripalpis Town;. (19) Phoroccra dory- 
phorw Riley ; Muscidse: (20) Luc ilia cwsar L. ; (21) Musca do- 
mestica L. ; Anthomyidae : (22) Leucomelina garrula, Gig. — 
Tos. ; (23) Anthomyia sp. ; (24) Phorbia fusciceps Zett. — all s. 
or f. p. 
c. lepidoptera. 
Rhopalocera: (25) Pyrantels huntera Fabr. s. ; (26) Pontia 
rapw L. s. 
The most important pollinators are large flies, especially 
Syrphidae, and an oligotropic bee Andrcna pamassice Ckll. A dy 
by landing in the middle of a flower in the first stage becomes 
dusted with pollen on the lower side of its body, and afterwards 
brings the same part of its body in contact with the receptive 
stigma when visiting a flower in the second stage. Andrcna 
pamassiw the bee specially adapted to Pamassia Caroliniana (6) 
always alights on the middle of the flower and bends the front 
part of its body (head and thorax) down on one side of the ovary, 
and the abdomen on the other side, thereby collecting pollen and 
nectar in the staminate stage, and nectar alone in the pistillate 
stage. 
6. S. Graenicher. The Relations of the Andrenine Bees to the 
Entomophilons Flora of Milwaukee County. Trans. Wis. Acad., XV, 
Tart I, pp. 94-95. 
