Note 2 — Chapter VII · INSTINCT AND DISCERNMENT

The variety of places where the insect installs itself, so eloquent of the part played by discernment in their selection, becomes still more remarkable when accompanied by a corresponding variety in the architecture of the cells. This is more particularly the case with the Three-horned Osmia,2 who, as she uses clayey materials very easily affected by the rain, requires, like the Pelopæus, a dry shelter for her cells, a shelter which she finds ready-made and uses just as it is, after a few touches by way of sweeping and cleansing. The homes which I see her adopt are especially the shells of Snails that have died under the stone-heaps and in the low, unmortared walls which support the cultivated earth of the hills in shelves or terraces. The use of Snail-shells is accompanied by the no less active use of the old cells of both the Mason-bee of the Sheds and of certain Anthophoræ (A. pilipes, A. parietina and A. personata.)3