HO ENTOMOLOGICAL NEWS. [March, '13 



of Andrena. In Milwaukee County, Wis., according to 

 Graenicher, there are then n species of Andrena on the 

 wing; and all of them, with one exception, are oligotropic 

 visitors of the Compositae. The single exception (A. par- 

 nassiae) is found only near Whitefish Bay, Lake Michigan, 

 where Parnassia caroliniana produces a great abundance of 

 flowers. Evidently this bee gets its pollen from these flow- 

 ers because they are very abundant in the one locality where 

 it is known. As stated above all the other species, ten in 

 number, are oligotropic to the Compositae. Many genera of 

 this family are excessively common, as the golden rods, as- 

 tcrs, sunflowers and thoroughworts, and yield immense quan- 

 tities of nectar and pollen. There are very strong induce- 

 ments for these bees to visit these flowers, and comparatively 

 little for them to go elsewhere. These oligotropic species of 

 Andrena cannot visit the Compositae to avoid competition 

 with other species of the same genus because there are no 

 other species flying. Nor can they receive any benefit from 

 other species visiting the flowers of other families for the 

 same reason the entire absence of such Andrenid bees. 

 There is but one explanation possible, and that is that they 

 visit the Compositae exclusively for the direct advantages 

 thus obtained. 



This point is still further illustrated by four autumnal spe- 

 cies of Andrena, ,which in New England restrict their visits 

 chiefly to the golden rods. The various species of Solidagp 

 are extremely common and occur in the most diverse situa- 

 tions from marine beaches to high, open woodlands. For a 

 time honey bees visit almost exclusively the inflorescence of 

 this genus, from which annually they gather tons of honey 

 and a great amount of pollen. The visits of the domestic 

 bee are not the result of competition, but solely because of 

 the advantages gained. For the same reason Andrena cana- 

 denstis, A. nitbccnla, A. hirticincta and A. solidaginis g*et 

 their pollen and nectar mostly from this genus. 



Halictoidcs novae-angliae , as already stated, visits exclu- 

 sively in this locality the spikes of the pickerel weed (Ponte- 



