r supplied with teeth or not, does not
account at all for the two manufactures. May we, in this predicament,
have recourse to the general structure of the insect, although this is
not distinctive enough to be of much use to us? Not so either; for,
in the same stone-heaps where the Osmia and the two Resin-bees of the
Snail-shells work, I find from time to time another manipulator of
mastic who bears no structural relationship whatever to the genus
Anthidium. It is a small-sized Mason-wasp, Odynerus alpestris, SAUSS.
She builds a very pretty nest with resin and gravel in the shells of
the young Common Snail, of Helix nemoralis and sometimes of Bulimulus
radiatus. I will describe her masterpiece on some other occasion. To
one acquainted with the genus Odynerus, any comparison with the Anthidia
would be an inexcusable error. In larval diet, in shape, in habits, they
form two dissimilar groups, very far removed one from the other. The
Anthidia feed their offspring on honey-bread; the Odyneri feed it on
live prey. Well, with her slender form, her weakly frame, in which
the most clear-seeing eye would seek in vain for a clue to the trade
practised, the Alpine Odynerus, the game-lover, uses pitch in the same
way as the stout and massive Resin-bee, the honey-lover. She even uses
it better, for her mosaic of tiny pebbles is much prettier than the
Bee's and no less solid. With her mandibles, this time neither spoon nor
rake, but rather a long forceps slightly notched at the tip, she gathers
her drop of sticky matter as dexterously as do her rivals with their
very different outfit. Her case will, I think, persuade us that neither
the shape of the tool nor the shape of the worker can explain the work
done.

I will go further: I ask myself in vain the reason of this or that trade
in the case of a fixed species. The Osmiae make their partitions with
mud or with a paste of chewed leaves; the Mason-bees build with cement;
the Pelopaeus-wasps fashion clay pots; the Megachiles made disks
cut from leaves into urns; the Anthidia felt cotton into purses;
the Resin-bees cement together little bits of gravel with gum; the
Carpenter-bees and the Lithurgi bore holes in timber; the Anthophorae
tunnel the roadside slopes. Why all these different trades, to say
nothing of the others? How are they prescribed for the insect, this one
rather than that?

I foresee the answer: they are prescribed by the organization. An insect
excellently equipped for