o the tastes of their particular genus.

For the sake of clearness, let us cease generalizing and direct our
attention to a definite species. I first selected the White-girdled
Leaf-cutter (Megachile albocincta, PEREZ), not on account of any
exceptional peculiarities, but solely because this is the Bee most
often mentioned in my notes. Her customary dwelling is the tunnel of an
Earth-worm opening on some clay bank. Whether perpendicular or slanting,
this tunnel runs down to an indefinite depth, where the climate would be
too damp for the Bee. Besides, when the time comes for the hatching of
the adult insect, its emergence would be fraught with peril if it had
to climb up from a deep pit through crumbling rubbish. The Leaf-cutter,
therefore, uses only the front portion of the Worm's gallery, two
decimetres at most. (7.8 inches.--Translator's Note.) What is to be done
with the rest of the tunnel? It is an ascending shaft, tempting to an
enemy; and some underground ravager might come this way and destroy the
nest by attacking the row of cells at the back.

The danger is foreseen. Before fashioning her first honey-bag, the
Bee blocks the passage with a strong barricade composed of the only
materials used in the Leaf-cutter's guild. Fragments of leaves are
piled up in no particular order, but in sufficient quantities to make
a serious obstacle. It is not unusual to find in the leafy rampart some
dozens of pieces rolled into screws and fitting into one another like
a stack of cylindrical wafers. For this work of fortification, artistic
refinement seems superfluous; at any rate, the pieces of leaves are for
the most part irregular. You can see that the insect has cut them out
hurriedly, unmethodically and on a different pattern from that of the
pieces intended for the cells.

I am struck with another detail in the barricade. Its constituents
are taken from stout, thick, strong-veined leaves. I recognize young
vine-leaves, pale-coloured and velvety; the leaves of the whitish
rock-rose (Cistus albidus), lined with a hairy felt; those of the
holm-oak, selected among the young and bristly ones; those of the
hawthorn, smooth but tough; those of the cultivated reed, the only one
of the Monocotyledones exploited, as far as I know, by the Megachiles.
In the construction of cells, on the other hand, I see smooth leaves
predominating, notably those of the wild briar and of the common acacia,
the robinia. It would appear, therefore, th