96 Wisconsin Academy of Sciences, Arts, and Letters. 
To these I add 11 species recognized 
surroundings: 
Name of species. 
Andrena cockerelli, Graen. 
Andrena fragariana, Graen. 
Andrena thaspii, Graen. 
Andrena wheeleri , Graen. 
Andrena albofoveata, Graen. 
Andrena peckhami , Ckll. 
Andrena clypeonitens, Ckll. 
Andrena americana, D. T. 
Andrena persimilis, Graen. 
Andrena graenicheri, Ckll. 
Andrena parnassiae, Ckll. 
as oligotropic bees of our 
Plants visited for pollen. 
Salix. 
Fragaria Yirginiana. 
Umbelliferae. 
Umbelliferae. 
Umbelliferae. 
Gompositae. 
Compositae. 
Gompositae. 
Gompositae. 
Gompositae. 
Parnassia Garolimana. 
According to this list 24 of the 47 species of Andreninae con¬ 
sidered in this paper, or fully one-half are oligotropic. The 
Compositae supply 10 of these with pollen, and the willows come 
next with 5 oligotropic bees. The importance of the TJmbelli- 
ferae in this respect is also evident, 4 such visitors being adapted 
to them. As regards Andrena gcranii this bee figures in Bob- 
ertson’s list as an oligotropic species of Hydrophyllum appendi- 
cidalum, but in our surroundings it collects pollen from Hydro - 
phyllum Virginicum, the only representative of that genus in 
our flora, and it therefore has to be considered an oligotropic 
bee of the genus Hydrophyllum. 
Seasonal forms. There are numerous instances recorded of 
an insect-species appearing at one period of the season in a form 
differing more or less from the form assumed at another period. 
These are called seasonal forms. A few cases are mentioned in 
the literature, all of them from the Eastern states, in which a 
species of Andrena taken later in the season has been regarded 
as identical with some species flying in the spring. Observa¬ 
tions carried on throughout a number of years warrant the 
statement, that in our region no seasonal forms of Andrena oc¬ 
cur. Species after species makes its appearance in the order 
indicated in the list at the beginning of this paper. As regards 
their time of flight there is a great diversity among the different 
species, some of them flying over 2 months, while others are 
