The Anthophora's cells contain this bee in the larval stage. Some
of them provide me with the oil beetle and the Sitaris, rare finds
at one time, today of no use to me. Others contain the Melecta [a
parasitic bee] in the form of a highly colored pupa, or even in
that of the full grown insect. The Osmia, still more precocious,
though dating from the same period, shows herself exclusively in
the adult form, a bad omen for my investigations, for what the
Anthrax demands is the larva and not the perfect insect. The fly's
grub doubles my apprehensions. Its development is complete, the
larva on which it feeds is consumed, perhaps several weeks ago. I
no longer doubt but that I have come too late to see what happens
in the Osmia's cocoons.

Is the game lost? Not yet. My notes contain evidence of Anthrax
flies hatching in the latter half of September. Besides, those
whom I now see exploring the rock are not there to take exercise:
their preoccupation is the settling of the family. These belated
ones cannot tackle the Osmia, who, with her firm, adult flesh,
would not suit the nursling's delicate needs and who, moreover,
powerful as she is, would offer resistance. But in autumn a less
numerous colony of honey gatherers takes the place, upon the
slope, of the spring colony, from which it differs in species. In
particular, I see the Diadem Anthidium [a clothier bee who lines
her nest with wool and cotton] at work, entering her galleries at
one time with her harvest of pollen dust and at another with her
little bale of cotton. Might not these autumnal Bees be
themselves exploited by the Anthrax, the same that selected the
Osmia as her victim a couple of months earlier? This would
explain the presence of the Anthrax flies whom I now see fussing