At last each has made her choice. The work of construction begins;and my expectations are fulfilled far beyond my wishes. The Osmiae build nests in all the retreats which I have placed at their disposal. The glass tubes, which I cover with a sheet of paper to produce the shade and mystery favourable to concentrated toil, do wonderfully well. All, from first to last, are occupied. The Osmiae quarrel for the possession of these crystal palaces, hitherto unknown to their race. The reeds and the paper tubes likewise do wonderfully.
The number provided is too small; and I hasten to increase it. Snail-shells are recognized as excellent abodes, though deprived of the shelter of the stone-heap; old Chalicodoma-nests, down to those of the Chalicodoma of the Shrubs (Cf. "The Mason-bees": chapters 4 and 10.--Translator's Note.), whose cells are so small, are eagerly occupied. The late-comers, finding nothing else free, go and settle in the locks of my table-drawers. There are daring ones who make their way into half-open boxes containing ends of glass tubes in which I have stored my most recent acquisitions: grubs, pupae and cocoons of all kinds, whose evolution I wished to study. Whenever these receptacles have an atom of free space, they claim the right to build there, whereas I formally oppose the claim. I hardly reckoned on such a success, which obliges me to put some order into the invasion with which I am threatened. I seal up the locks, I shut my boxes, I close my various receptacles for old nests, in short Iremove from the building-yard any retreat of which I do not approve.
And now, O my Osmiae, I leave you a free field!
The work begins with a thorough spring-cleaning of the home. Remnants of cocoons, dirt consisting of spoilt honey, bits of plaster from broken partitions, remains of dried Mollusc at the bottom of a shell:
these and much other insanitary refuse must first of all disappear.
Violently the Osmia tugs at the offending object and tears it out;and then off she goes, in a desperate hurry, to dispose of it far away from the study. They are all alike, these ardent sweepers: in their excessive zeal, they fear lest they should block up the place with a speck of dust which they might drop in front of the new house.
The glass tubes, which I myself have rinsed under the tap, are not exempt from a scrupulous cleaning. The Osmia dusts them, brushes them thoroughly with her tarsi and then sweeps them out backwards. What does she pick up? Not a thing. It makes no difference: as a conscientious housewife, she gives the place a touch of the broom nevertheless.
Now for the provisions and the partition-walls. Here the order of the work changes according to the diameter of the cylinder. My glass tubes vary greatly in dimensions. The largest have an inner width of a dozen millimetres (Nearly half an inch.--Translator's Note.); the narrowest measure six or seven. (About a quarter of an inch.--Translator's Note.) In the latter, if the bottom suit her, the Osmia sets to work bringing pollen and honey. If the bottom do not suit her, if the sorghum-pith plug with which I have closed the rear-end of the tube be too irregular and badly-joined, the Bee coats it with a little mortar. When this small repair is made, the harvesting begins.
In the wider tubes, the work proceeds quite differently. At the moment when the Osmia disgorges her honey and especially at the moment when, with her hind-tarsi, she rubs the pollen-dust from her ventral brush, she needs a narrow aperture, just big enough to allow of her passage. I imagine that, in a straitened gallery, the rubbing of her whole body against the sides gives the harvester a support for her brushing-work. In a spacious cylinder, this support fails her;and the Osmia starts with creating one for herself, which she does by narrowing the channel. Whether it be to facilitate the storing of the victuals or for any other reason, the fact remains that the Osmia housed in a wide tube begins with the partitioning.
Her division is made by a dab of clay placed at right angles to the axis of the cylinder, at a distance from the bottom determined by the ordinary length of a cell. This wad is not a complete round; it is more crescent-shaped, leaving a circular space between it and one side of the tube. Fresh layers are swiftly added to the dab of clay;and soon the tube is divided by a partition which has a circular opening at the side of it, a sort of dog-hole through which the Osmia will proceed to knead the Bee-bread. When the victualling is finished and the egg laid upon the heap, the hole is closed and the filled-up partition becomes the bottom of the next cell. Then the same method is repeated, that is to say, in front of the just completed ceiling a second partition is built, again with a side-passage, which is stouter, owing to its distance from the centre, and better able to withstand the numerous comings and goings of the housewife than a central orifice, deprived of the direct support of the wall, could hope to be. When this partition is ready, the provisioning of the second cell is effected; and so on until the wide cylinder is completely stocked.
The building of this preliminary party-wall, with a narrow, round dog-hole, for a chamber to which the victuals will not be brought until later is not restricted to the Three-horned Osmia; it is also frequently found in the case of the Horned Osmia and of Latreille's Osmia. Nothing could be prettier than the work of the last-named, who goes to the plants for her material and fashions a delicate sheet in which she cuts a graceful arch. The Chinaman partitions his house with paper screens; Latreille's Osmia divides hers with disks of thin green cardboard perforated with a serving-hatch which remains until the room is completely furnished. When we have no glass houses at our disposal, we can see these little architectural refinements in the reeds of the hurdles, if we open them at the right season.
