20 Bulletin Wisconsin Natural History Society. [Vol. 7, Nos. 1-2. 



ation of floral organs is of secondary importance only. According 

 to his opinion the pollination of flowers by insects would take 

 place just the same if all the flowers were of green color like the 

 leaves. Stimulated by Plateau's publications quite a number of 

 investigators have taken up work along this line, and although the 

 results obtained have led to views that are more or less conflicting, 

 still the fact seems to be established, that a flower visiting insect 

 does not show a preference for any particular color. According 

 to Lovell 6 "the colors of flowers both in general and particular 

 have been determined by their utility rather than by an aesthetic 

 color sense in insects. Insects distinguish between different 

 colors, but they do not receive greater pleasure from one hue than 

 from another." Referring to the fact that among the Compositae 

 those species that are the most extensively visited by insects display 

 a variety of colors(yellow goldenrods, white yarrow, purple Canada 

 thistle, etc.) Lovell 7 states that "these differently colored species 

 are visited by a large company of Hymenoptera, Lepidoptera, Dip- 

 tera and Coleoptera, which are influenced by the length of the 

 corolla tube and the degree of conspicuousness obtained by a con- 

 trast of colors and by massing." 



The tubal florets of our species of Compositae, although very 

 similar in structure differ considerably in their dimensions (es- 

 pecially in length) ; they differ also in color, and odor. From a 

 comparison of the lists of visitors of such flowers of equal tube 

 length but of different color and odor some direct information 

 as to the effect of color or odor on insects might be expected. 

 With this end in view, a number of species (37 are dealt with in 

 this paper) have been studied, representing the different tube 

 lengths (from the shortest tube in Erigeron canadensis to the 

 longest in Cirsium aliissimum and C. lanccolatnm), different col- 

 ors, (white, yellow, blue and purple) and different odors. For 

 the purpose of obtaining as large numbers of visitors as possible 

 these observations have been carried on for the last 3 seasons, 

 and altogether the following 562 species of insects have been taken 

 at the flowers under consideration. The lists of visitors are rather 

 long for most of the species, over 100 in some, and even 182 in 

 the goldenrod Solidago juncca. Quite a number of the more com- 

 mon insects appear as visitors to most of the flowers, and an ap- 

 pearance of the names of all these in full in each of the lists 

 would occupy more space than would seem justifiable. For the 



6) John H. Lovell. The colors of northern gamopetalous flowers. Am- 

 erican Naturalist, Vol. XXXVII., No. 439, p. 478, (July 1903). 

 7) Loc. cit., p. 452. 



