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the case of Anthidium scapulare. The insects divided themselves into two equal batches, one going to the right, the other to the left. Tripoxylon figulus left me undecided. This feeble insect is not capable of perforating my partitions; it nibbles at them a little; and I had to judge the direction from the marks of its mandibles. These marks, which are not always very plain, do not yet allow me to pronounce an opinion. Solenius vagus, who is a skilful borer, behaved differently from the Osmia. In a column of ten, the whole exodus was made in one direction.
On the other hand, I tested the Mason-bee of the Sheds, who, when emerging under natural conditions, has only to pierce her cement ceiling and is not confronted with a series of cells. Though a stranger to the environment which I created for her, she gave me a most positive answer. Of a column of ten laid in a horizontal tube open at both ends, five made their way to the right and five to the left. Dioxys cincta, a parasite in the buildings of both species of Mason-bees, the Chalicodoma of the Sheds and the Chalicodoma of the Walls (Cf. "The Mason-bees" by J. Henri Fabre, translated by Alexander Teixeira de Mattos: passim.--Translator's Note.), provided me with no precise result. The Leaf-cutting Bee (Megachile apicalis, SPIN. (Cf. Chapter 8 of the present volume.--Translator's Note.)), who builds her leafy cups in the old cells of the Chalicodoma of the Walls, acts like the Solenius and directs her whole column towards the same outlet.
Incomplete as it is, this symmetry shows us how unwise it were to generalize from the conclusions to which the Three-pronged Osmia leads us. Whereas some Bees, such as the Anthidium and the Chalicodoma, share the Osmia's talent for using the twofold exit, others, such as the Solenius and the Leaf-cutter, behave like a flock of sheep and follow the first that goes out. The entomological world is not all of a piece; its gifts are very various: what one is capable of doing another cannot do; and penetrating indeed would be the eyes that saw the causes of these differences. Be this as it may, increased research will certainly show us a larger number of species qualified to use the double outlet. For the moment, we know three; and that is enough for our purpose.
I will add that, when the horizontal tube has one of its ends closed, the whole string of Osmiae makes for the open end, turning round to do so, if need be.
Now that the facts are set forth, let us, if possible, trace the cause. In a horizontal tube, gravity no longer acts to determine the direction which the insect will take. Is it to attack the partition on the right or that on the left? How shall it decide? The more I look into the matter, the more do my suspicions fall upon the atmospheric influence which is felt through the two open ends. Of what does this influence consist? Is it an effect of pressure, of hygrometry, of electrical conditions, of properties that escape our coarser physical attunement? He were a bold man who should undertake to decide. Are not we ourselves, when the weather is about to alter, subject to subtle impressions, to sensations which we are unable to explain? And yet this vague sensitiveness to atmospheric changes would not be of much help to us in circumstances similar to those of my anchorites. Imagine ourselves in the darkness and the silence of a prison-cell, preceded and followed by other similar cells. We possess implements wherewith to pierce the walls; but where are we to strike to reach the final outlet and to reach it with the least delay? Atmospheric influence would certainly never guide us.
And yet it guides the insect. Feeble though it be, through the multiplicity of partitions, it is exercised on one side more than on the other, because the obstacles are fewer; and the insect, sensible to the difference between those two uncertainties, unhesitatingly attacks the partition which is nearer to the open air. Thus is decided the division of the column into two converse sections, which accomplish the total liberation with the least aggregate of work. In short, the Osmia and her rivals 'feel' the free space. This is yet one more sensory faculty which evolution might well have left us, for our greater advantage. As it has not done so, are we then really, as many contend, the highest expression of the progress accomplished, throughout the ages, by the first atom of glair expanded into a cell?
CHAPTER 2. THE OSMIAE.
February has its sunny days, heralding spring, to which rude winter will reluctantly yield place. In snug corners, among the rocks, the great spurge of our district, the characias of the Greeks, the jusclo of the Provencals, begins to lift its drooping inflorescence and discreetly opens a few sombre flowers. Here the first Midges of the year will come to slake their thirst. By the time that the tip of the stalks reaches the perpendicular, the worst of the cold weather will be over.
Another eager one, the almond-tree, risking the loss of its fruit, hastens to echo these preludes to the festival of the sun, preludes which are too often treacherous. A few days of soft skies and it becomes a glorious dome of white flowers, each twinkling with a roseate eye. The country, which still lacks green, seems dotted everywhere with white-satin pavilions. 'Twould be a callous heart indeed that could resist the magic of this awakening.
The insect nation is represented at these rites by a few of its more zealous members. There is first of all the Honey-bee, the sworn enemy of strikes, who profits by the least lull of winter to find out if some rosemary is not beginning to open somewhere near the hive. The droning of the busy swarm fills the flowery vault, while a snow of petals falls softly to the foot of the tree.
Together with the population of harvesters there mingles another, less numerous, of mere drinkers, whose nesting-time has not yet begun. This is the colony of the Osmiae, with their copper-coloured skin and bright-red fleece. Two species have come hurrying up to take part in the joys of the almond-tree: first, the Horned Osmia, clad in black velvet on the head and breast and in red velvet on the abdomen; and, a little later, the Three-horned Osmia, whose livery must be red and red only. These are the first delegates despatched by the pollen- gleaners to ascertain the state of the season and attend the festival of the early blooms. 'Tis but a moment since they burst their cocoon, the winter abode: they have left their retreats in the crevices of the old walls; should the north wind blow and set the almond-tree shivering, they will hasten to return to them. Hail to you, O my dear Osmiae, who yearly, from the far end of the harmas (The piece of waste ground in which the author studied his insects in their natural state. Cf. "The Life of the Fly" by J. Henri Fabre, translated by Alexander Teixeira de Mattos: chapter 1.--Translator's Note.), opposite snow-capped Ventoux (A mountain in the Provencal Alps, near Carpentras and Serignan, 6,271 feet.--Translator's Note.), bring me the first tidings of the awakening of the insect world! I am one of your friends; let us talk about you a little.
Most of the Osmiae of my region have none of the industry of their kinswomen of the brambles, that is to say, they do not themselves prepare the dwelling destined for the laying. They want ready-made lodgings, such as the old cells and old galleries of Anthophorae and Chalicodomae. If these favourite haunts are lacking, then a hiding- place in the wall, a round hole in some bit of wood, the tube of a reed, the spiral of a dead Snail under a heap of stones are adopted, according to the tastes of the several species. The retreat selected is divided into chambers by partition-walls, after which the entrance to the dwelling receives a massive seal. That is the sum-total of the building done.
For this plasterer's rather than mason's work, the Horned and the Three-horned Osmia employ soft earth. This material is different from the Mason-bee's cement, which will withstand wind and weather for many years on an exposed pebble; it is a sort of dried mud, which turns to pap on the addition of a drop of water. The Mason-bee gathers her cementing-dust in the most frequented and driest portions of the road; she wets it with a saliva which, in drying, gives it the consistency of stone. The two Osmiae who are the almond-tree's early visitors are no chemists: they know nothing of the making and mixing of hydraulic mortar; they limit themselves to gathering natural soaked earth, mud in short, which they allow to dry without any special preparation on their part; and so they need deep and well- sheltered retreats, into which the rain cannot penetrate, or the work would fall to pieces.
While exploiting, in friendly rivalry with the Three-horned Osmia, the galleries which the Mason-bee of the Sheds good-naturedly surrenders to both, Latreille's Osmia uses different materials for her partitions and her doors. She chews the leaves of some mucilaginous plant, some mallow perhaps, and then prepares a sort of green putty with which she builds her partitions and finally closes the entrance to the dwelling. When she settles in the spacious cells of the Masked Anthophora (Anthophora personata, ILLIG.), the entrance to the gallery, which is wide enough to admit one's finger, is closed with a voluminous plug of this vegetable paste. On the earthy banks, hardened by the sun, the home is then betrayed by the gaudy colour of the lid. It is as though the authorities had closed the door and affixed to it their great seals of green wax.
So far then as their building-materials are concerned, the Osmiae whom I have been able to observe are divided into two classes: one building compartments with mud, the other with a green-tinted vegetable putty. The first section includes the Horned Osmia and the Three-horned Osmia, both so remarkable for the horny tubercles on their faces.
The great reed of the south, the Arundo donax, is often used, in the country, for rough garden-shelters against the mistral or just for fences. These reeds, the ends of which are chopped off to make them all the same length, are planted perpendicularly in the earth. I have often explored them in the hope of finding Osmia-nests. My search has very seldom succeeded. The failure is easily explained. The partitions and the closing-plug of the Horned and of the Three-horned Osmia are made, as we have seen, of a sort of mud which water instantly reduces to pap. With the upright position of the reeds, the stopper of the opening would receive the rain and would become diluted; the ceilings of the storeys would fall in and the family would perish by drowning. Therefore the Osmia, who knew of these drawbacks before I did, refuses the reeds when they are placed perpendicularly.
The same reed is used for a second purpose. We make canisses of it, that is to say, hurdles, which, in spring, serve for the rearing of silk-worms and, in autumn, for the drying of figs. At the end of April and during May, which is the time when the Osmiae work, the canisses are indoors, in the silk-worm nurseries, where the Bee cannot take possession of them; in autumn, they are outside, exposing their layers of figs and peeled peaches to the sun; but by that time the Osmiae have long disappeared. If, however, during the spring, an old, disused hurdle is left out of doors, in a horizontal position, the Three-horned Osmia often takes possession of it and makes use of the two ends, where the reeds lie truncated and open.
There are other quarters that suit the Three-horned Osmia, who is not
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