My method is extremely simple. All I ask is that the birth of my insects, that is to say, their first seeing the light, their emerging from the cocoon, should take place on the spot where I propose to make them settle. Here there must be retreats of no matter what nature, but of a shape similar to that in which the Osmia delights. The first impressions of sight, which are the most long-lived of any, shall bring back my insects to the place of their birth. And not only will the Osmiae return, through the always open windows, but they will always nidify on the natal spot if they find something like the necessary conditions. And so, all through the winter, I collect Osmia-cocoons, picked up in the nests of the Mason-bee of the Sheds; I go to Carpentras to glean a more plentiful supply in the nests of the Hairy-footed Anthophora, that old acquaintance whose wonderful cities I used to undermine when I was studying the history of the Oil-beetles. (This study is not yet translated into English; but cf. "The Life of the Fly": chapters 2 and 4.--Translator's Note.) Later, at my request, a pupil and intimate friend of mine, M. Henri Devillario, president of the civil court at Carpentras, sends me a case of fragments broken off the banks frequented by the Hairy-footed Anthophora and the Anthophora of the Walls, useful clods which furnish a handsome adjunct to my collection. Indeed, at the end, I find myself with handfuls of cocoons of the Three-horned Osmia. To count them would weary my patience without serving any particular purpose. I spread out my stock in a large open box on a table which receives a bright diffused light but not the direct rays of the sun. The table stands between two windows facing south and overlooking the garden. When the moment of hatching comes, those two windows will always remain open to give the swarm entire liberty to go in and out as it pleases. The glass tubes and the reed-stumps are laid here and there, in fine disorder, close to the heap of cocoons and all in a horizontal position, for the Osmia will have nothing to do with upright reeds. The hatching of some of the Osmiae will therefore take place under cover of the galleries destined to be the building-yard later; and the site will be all the more deeply impressed on their memory. When I have made these comprehensive arrangements, there is nothing more to be done; and I wait patiently for the building-season to open.