To the Editor of the Popular Science Monthly.
IN my paper on "The Fertilization of Flowers by Insect Agency" ("Proceedings of the American Association for the Advancement of Science," 1875, pp. 244, 245), I say: "On my first visit to the Rocky Mountain region, the absence of insects proved very annoying to the entomologists who accompanied me. Indeed, the paucity of animal life of all kinds in the Rocky Mountains is well known; but there is no more scarcity of seed in the colored flowering plants than in similar ones elsewhere." At the conclusion of my address, Prof. Riley objected to the accuracy of this statement—not from his own personal experience, as I believe, and from overlooking, as I supposed, that I was referring to insects relating to the cross-fertilization of flowers—chiefly Hymenoptera and Lepidoptera. Mr. Charles R. Dodge, editor of Field and Forest, was one of the entomologists I referred to. In vol. i., No. 12, page 89, he describes that expedition in the summer of 1871: "The route carried us through Golden City and Idaho Springs to South Park, thence to Pike's Peak and the Garden of the Gods, where we emerged from the mountains and returned to Denver over the level plateau known as the 'Divide;' and, from the time we passed the foot-hills near Golden City, and entered the first canon in the mountains, we were struck with the comparative paucity of the insect fauna. ... In the mountains, the marked absence of insect-life in variety, except in favorable localities, was the rule, and not the exception." Traveling was not so easy then as now, and I think it took us nearly three weeks. The party comprised thirty persons, all of whom were interested in aiding the collectors. Mr. Dodge sums up his remarks by especially noting that "the entire mountain-trip yielded so small a number of nocturnal Lepidoptera that they are hardly worth mentioning." He adds, "I have conversed with a few other entomologists on this subject, and they agree with me perfectly."
Now, if we turn to Hayden's "Report of the Survey of Colorado," for 1873, we find Lieutenant Carpenter substantially recording the same thing. Here are the doings of a whole season, and not for three weeks merely, and only five species of butterflies are found; and, indeed, he remarks that "Lepidoptera are undoubtedly peculiar to high latitudes and great elevations." This leaves us with scarcely anything but bees to do the whole work of flower-fertilization in the Rocky Mountain region. But even these seem to be confined to some considerable elevation. In an expedition in 1873 I saw Bombus termarius in abundance, but on no other flowers than Polygonum bistorta, on Gray's Peak, on the flats near the timber-line. I was struck by the fact that they seemed to visit only this species, evidently getting all they required from it, and neglecting everything else. I did not see bees anywhere in our expedition of 1871 in lower altitudes, nor do I think there were any in 1873, except in this high region near the timber-line. Of course, there might have been, but, if so, they were so scarce as to attract little attention. This seems to have been the experience of Lieutenant Carpenter. He says, "The bumble-bee was always to be seen in midsummer at the verge of the Alpine flora, busily engaged in collecting its store of pollen from the few flowers to be found." This does not certainly say they might not be found lower down, but it is a fair inference. My collections in this district embraced over seven hundred species of flowering plants and ferns. I can say that among these were quite as large a proportion of colored flowers as in an equal number gathered East, where insects are conceded to be numerous.
But just here Prof. Gray steps in with the following note: "A propos to Mr. Meehan's suggestion that, although the Alpine plants of the Colorado Rocky Mountains are mostly high colored, insects are there so rare that they can be of no material aid to fertilization, and therefore these plants