Let us go to the slope of the hills thick with olive-trees and inspect the little supporting-walls which are built of dry stones and face the south.

In the crevices of this insecure masonry we shall reap a harvest of old Snail-shells, plugged with earth right up to the orifice.

The family of the Three-horned Osmia is settled in the spiral of those shells, which is subdivided into chambers by mud partitions.
The Three-pronged Osmia (O.Tridentata, Duf.

and Per.) alone creates a home of her own, digging herself a channel with her mandibles in dry bramble and sometimes in danewort.
The Osmia loves mystery.

She wants a dark retreat, hidden from the eye.
I would like, nevertheless, to watch her in the privacy of her home and to witness her work with the same facility as if she were nest-building in the open air.