These varying habits in the same species
show pretty clearly that these little creatures are not driven by any blind instinct in the adoption of their methods of nest building: they appear to have a distinct power of choice and adaptation according to their environment, unless of course it can be shown that the offspring of, say, a snail shell inhabitant follows its parents' habits, and that that of a ground borer does the same—but even that would not explain the case given by F. Smith, and quoted above, where an Osmia had filled up the whorls of a shell and then, finding the final whorl too large, placed two cells horizontally to fill it: that seems to indicate distinct design on the part of the bee and would be hard to explain as due to instinct. Unfortunately, with the exception of a very few, the species of Osmia are rare in this country, so that few opportunities are available for studying their habits, which are certainly amongst the most interesting of any genus.
24. Anthophora pilipes, male. 25. Anthophora pilipes, female. 26. Melecta armata, female. 27. Anthidium manicatum, female. 28. Osmia bicolor, female. 29. Bombus terrestris, female. 30. Bombus lapidarius. female. 31. Psithyrus rupestris, female.
[face p. 61.
A COLONY OF ANTHOPHORA
Anthophora pilipes ([pl. D], 24, 25), one of our early spring bees, often forms enormous colonies. I have sometimes seen sandpits in which the sides were riddled all over with holes of this species, and where the insects were in such numbers that a distinct hum was audible from the vibration of their wings. In such colonies one is sure to detect some of their cuckoo associates, Melecta armata ([pl. D], 26). They are deep black bees, much of the same size as their hosts but with more pointed tails and with a small spot of snow-white hairs on the side of each segment of the body; like other cuckoos they sail about in a more demure way than their hosts, but a more lively scene than a large colony of Anthophora can hardly be found. The Anthophora provisions its cells with honey and pollen, and its egg in consequence floats on the top—the
number of cells varies from five or six up to ten or eleven.