questions suggested to me, in the end, by Monodontomerus cupreus,
the insect so infinitesimal in body and so overpowering in name
that I had really vowed never to speak of it again by its official
designation.




CHAPTER IV LARVAL DIMORPHISM

If the reader has paid any attention to the story of the Anthrax,
he must have perceived that my narrative is incomplete. The fox in
the fable saw how the lion's visitors entered his den, but did not
see how they went out. With us, it is the converse: we know the
way out of the mason bee's fortress, but we do not know the way in.
To leave the cell of which he has eaten the owner, the Anthrax
becomes a perforating machine, a living tool from which our own
industry might take a hint if it required new drills for boring
rocks. When the exit tunnel is opened, this tool splits like a pod
bursting in the sun; and from the stout framework there escapes a
dainty fly, a velvety flake, a soft fluff that astounds us by its
contrast with the roughness of the depths whence it ascends. On
this point, we know pretty well what there is to know. There
remains the entrance into the cell, a puzzle that has kept me on
the alert for a quarter of a century.

To begin with, it is evident that the mother cannot lodge her egg
in the cell of the mason bee, which has been long closed and
barricaded with a cement wall by the time that the Anthrax makes
her appearance. To penetrate it, she would have to become an