110 The American Naturalist. [February, 
pollen brushes (Megachile, Fig. 32, Plate IX), and now in the 
case of this flower we find the principal visitors to be bees of 
the genus Osmia (Fig. 31, Plate IX) ; so thatit joins the red-bud 
and violet in appearing dusting the flight of these bees. The 
figwort (Scrophularia) and Symphoricarpus come late in adjust- 
ment to the flight of the wasp workers and Eumenidae to 
which they are specially adapted. The late position of the 
lobelias is what might be expected, since they are dependent 
upon the visits of the higher bees (Fig. 27, Plate IX). Wecome 
finally to consider the great highly specialized family of sun- 
flowers, nigger-heads, thistles, ete., (Compositae, Fig. 21,-2 spp. 
per mm. Plate IX) which shows a conspicuous late maximum 
and is the best example of Mr. Clarke’s theory, though I think 
one of the easiest to explain without it. 
The composite heads, which give the name to the family, 
are composed of florets arranged generally in a flat-topped 
horizontal layer which forms a convenient resting place for all 
kinds of insects. There is abundant nectar for the longer 
tongues and abundant pollen exposed for the least specialized 
to feed upon or to collect. From these peculiarities and from 
their great numbers we find this family to be of more impor- 
tance to the general insect fauna than any other. The most 
important visitors are the higher bees, especially bumble-bees 
(Fig. 30, Plate IX), the leaf-cutters (Fig. 32, Plate IX) and Melis- 
sodes (Fig. 29, Plate IX), and lower Aculeate Hymenoptera in 
general (Fig. 25, Plate IX), the butterflies (Fig. 23, Plate IX), the 
flies, including many flower-flies (Fig. 36, Plate X), the tachi- 
nids (Fig. 37, Plate I), the conopids (Fig. 38, Plate X), and the 
bombylids (Fig. 39, Plate X). The occurrence of the maximum 
of the family after that of the general flower-loving insect 
fauna, I think, is largely due to the abundance of the golden- 
rods, asters, etc., which have rather small heads and less-deeply 
concealed nectar. The position of these flowers is accounted 
for in correlation with the position of the usually smaller 
insects by which they are attended, viz.; the little bees belong- 
ing to the genera Calliopsis (Fig. 34, Plate IX), the late Colletes 
(Fig. 33, Plate IX), the autumnal group of Andrena (Fig. 35, Plate 
X) and the Bombylidae(Fig. 39, Plate X)—all important guests 
