the plants or going to the nest, the bee at this rate would visit six hundred blossoms an hour, or six thousand in a ten-hour day, if she should work so long. On the five acres of hilltop where my observations were carried on I judged that at least one hundred of these bees were at work each day. Supposing that they 
Fig. 6.—The Bee Fly. all worked at the above ratio, the mayflower would receive six hundred thousand daily visits. No doubt many of the blossoms are visited more than once each day, and the chances are certainly very good that each blossom will be visited at least once during the two weeks of its existence.
Although the orange-banded bumblebee is much the most abundant visitor, two other related species are often seen. The commoner of these is a large and handsome Bombus[1] black, except for two broad yellow bands one on the thorax and the other on the abdomen. The other, which is seldom seen, is called by entomologists Bombus consimilis; the thorax and front half of the abdomen are yellow, with the hinder portion of the abdomen black.
By watching any one of these bees closely, one can see it stop every few minutes to brush the pollen grains off from its tongue and head, but no attempt appears to be made to collect the pollen in the beautifully developed pollen baskets on the legs (Fig. 5). These bees evidently visit the arbutus for the nectar it furnishes. Although the bumblebees are much the most numerous and important of the mayflower's invited guests, a few other insects 
Fig. 7.—Sesia Moth are found among the visitors. A rather small, two-winged fly, with a hairy, yellow body and black-banded wings, often flashes, meteor-like, from blossom to blossom. This is the handsome bee fly of the genus Bombylius,[2] one of the earliest spring insects. It has a very long tongue, which readily reaches the bottom of the mayflower corollas. I saw one of these flies stop twenty seconds at a single flower; it thrust its tongue down on one side of the pistil, then drew it out and pushed it down in another place, repeating the operation four times.
During the warmest portions of the brightest days the beautiful sesia moths appear. They are sometimes called hummingbird moths, because of their resemblance when flying to a hum-
