The Golden Osmia (O. aurulenta, LATR.) absolutely insists on an empty Snail-shell as her residence. The Brown or Girdled Snail, the Garden Snail and especially the Common Snail, who has a more spacious spiral, all scattered at random in the grass, at the foot of the walls and of the sun-swept rocks, furnish her with her usual dwelling-house. Her dried putty is a kind of felt full of short white hairs. It must come from some hairy-leaved plant, one of the Boragineae perhaps, rich both in mucilage and the necessary bristles.
The Red Osmia (O. rufo-hirta, LATR.) has a weakness for the Brown Snail and the Garden Snail, in whose shells I find her taking refuge in April when the north-wind blows. I am not yet much acquainted with her work, which should resemble that of the Golden Osmia.
The Green Osmia (O. viridana, MORAWITZ) takes up her quarters, tiny creature that she is, in the spiral staircase of Bulimulus radiatus.
It is a very elegant, but very small lodging, to say nothing of the fact that a considerable portion is taken up with the green-putty plug. There is just room for two.
The Andrenoid Osmia (O. andrenoides, LATR.), who looks so curious, with her naked red abdomen, appears to build her nest in the shell of the Common Snail, where I discover her refuged.
The Variegated Osmia (O. versicolor, LATR.) settles in the Garden Snail's shell, almost right at the bottom of the spiral.
The Blue Osmia (O. cyanea, KIRB.) seems to me to accept many different quarters. I have extracted her from old nests of the Mason-bee of the Pebbles, from the galleries dug in a roadside bank by the Colletes (A short-tongued Burrowing-bee known also as the Melitta.--Translator's Note.) and lastly from the cavities made by some digger or other in the decayed trunk of a willow-tree.
Morawitz' Osmia (O. Morawitzi, PEREZ) is not uncommon in the old nests of the Mason-bee of the Pebbles, but I suspect her of favouring other lodgings besides.
The Three-pronged Osmia (O. tridentata, DUF. and PER.) creates a home of her own, digging herself a channel with her mandibles in dry bramble and sometimes in danewort. It mixes a few scrapings of perforated pith with the green paste. Its habits are shared by the Ragged Osmia (O. detrita, PEREZ) and by the Tiny Osmia (O. parvula, DUF.)The Chalicodoma works in broad daylight, on a tile, on a pebble, on a branch in the hedge; none of her trade-practises is kept a secret from the observer's curiosity. 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. Perhaps there are some interesting characteristics to be picked up in the depths of her retreats. It remains to be seen whether my wish can be realized.
When studying the insect's mental capacity, especially its very retentive memory for places, I was led to ask myself whether it would not be possible to make a suitably-chosen Bee build in any place that I wished, even in my study. And I wanted, for an experiment of this sort, not an individual but a numerous colony. My preference leant towards the Three-horned Osmia, who is very plentiful in my neighbourhood, where, together with Latreille's Osmia, she frequents in particular the monstrous nests of the Chalicodoma of the Sheds. Itherefore thought out a scheme for making the Three-horned Osmia accept my study as her settlement and build her nests in glass tubes, through which I could easily watch the progress. To these crystal galleries, which might well inspire a certain distrust, were to be added more natural retreats: reeds of every length and thickness and disused Chalicodoma-cells taken from among the biggest and the smallest. A scheme like this sounds mad. I admit it, while mentioning that perhaps none ever succeeded so well with me. We shall see as much presently.
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 2and 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.
