When the parasite is gone, I inspect the home. I see nothing abnormal on the surface of the mass. The sharper eye of the owner, when she gets back, sees nothing either, for she continues the victualling without betraying the least uneasiness. A strange egg, laid on the provisions, would not escape her. I know how clean she keeps her warehouse; I know how scrupulously she casts out anything introduced by my agency: an egg that is not hers, a bit of straw, a grain of dust. So, according to my evidence and that of the Chalicodoma, which is more conclusive, the Dioxys's egg, if it is really laid then, is not placed on the surface.
I suspect, without having yet verified my suspicion—and I reproach myself for the neglect—I suspect that the egg is buried in the heap of pollen-dust. When I see the Dioxys come out of a cell with her mouth all over yellow flour, perhaps she has been surveying the ground and preparing a hiding-place for her egg. What I take for a mere tasting might well be a more serious act. Thus concealed, the egg escapes the eagle eye of the Bee, whereas, if left uncovered, it would inevitably perish, would be flung on the rubbish heap at once by the owner of the nest. When the Spotted Sapyga lays her egg on that of the Bramble-dwelling Osmia, she does the deed under cover of darkness, in the gloom of a deep well to which not the least ray of light can penetrate; and the mother, returning with her pellet of green putty to build the closing partition, does not see the usurping germ and is ignorant of the danger. But here everything happens in broad daylight; and this demands more cunning in the method of installation.
Besides, it is the one favourable moment for the Dioxys. If she waits for the Mason-bee to lay, it is too late, for the parasite is not able to break down doors, as the Stelis does. As soon as her egg is laid, the Mason-bee of the Sheds comes out of her cell and at once turns round and proceeds to close it up with the pellet of mortar which she holds ready in her mandibles. The material is employed with such method that the actual sealing is done in a moment: the other pellets, the object of repeated journeys, will serve merely to increase the thickness of the lid. The chamber is inaccessible to the Dioxys from the first touch of the trowel. Hence it is absolutely necessary for her to see to her egg before the Mason-bee of the Sheds has disposed of hers and no less necessary to conceal it from the Mason's watchful eye.
The difficulties are not so great in the nests of the Mason-bee of the Pebbles. After this Bee has laid her egg, she leaves it for a time to go in search of the cement needed for closing the cell; or, if she already holds a pellet in her mandibles, this is not enough to seal it properly, as the orifice is larger. More pellets are needed to wall up the entrance entirely. The Dioxys would have time to strike her blow during the mother's absences; but everything seems to suggest that she behaves on the pebbles as she does on the tiles. She steals a march by hiding the egg in the mass of pollen and honey.
What becomes of the Mason's egg confined in the same cell with the egg of the Dioxys? In vain have I opened nests at every season; I have never found a vestige of the egg nor of the grub of either Chalicodoma. The Dioxys, whether as a larva on the honey, or enclosed in its cocoon, or as the perfect insect, was always alone. The rival had disappeared without a trace. A suspicion thereupon suggests itself; and the facts are so compelling that the suspicion is almost equal to a certainty. The parasitic grub, which hatches earlier than the other, emerges from its hiding-place, from the midst of the honey, comes to the surface and, with its first bite, destroys the egg of the Mason-bee, as the Sapyga does the egg of the Osmia. It is an odious, but a supremely efficacious method. Nor must we cry out too loudly against such foul play on the part of a new born infant: we shall meet with even more heinous tactics later. The criminal records of life are full of these horrors which we dare not search too deeply. An infinitesimal creature, a barely-visible grub, with the swaddling-clothes of its egg still clinging to it, is led by instinct, at its first inspiration, to exterminate whatever is in its way.
So the Mason's egg is exterminated. Was it really necessary in the Dioxys' interest? Not in the least. The hoard of provisions is too large for its requirements in a cell of the Chalicodoma of the Sheds; how much more so in a cell of the Chalicodoma of the Pebbles! She eats not a half, hardly a third of it. The rest remains as it was, untouched. We see here, in the destruction of the Mason's egg, a flagrant waste which aggravates the crime. Hunger excuses many things; for lack of food, the survivors on the raft of the Medusa indulged in a little cannibalism; but here there is enough food and to spare. When there is more than she needs, what earthly motive impels the Dioxys to destroy a rival in the germ stage? Why cannot she allow the larva, her mess-mate, to take advantage of the remains and afterwards to shift for itself as best it can? But no: the Mason-bee's offspring must needs be stupidly sacrificed on the top of provisions which will only grow mouldy and useless! I should be reduced to the gloomy lucubrations of a Schopenhauer if I once let myself begin on parasitism.
Such is a brief sketch of the two parasites of the Chalicodoma of the Pebbles, true parasites, consumers of provisions hoarded on behalf of others. Their crimes are not the bitterest tribulations of the Mason-bee. If the first starves the Mason's grub to death, if the second makes it perish in the egg, there are others who have a more pitiable ending in store for the worker's family. When the Bee's grub, all plump and fat and greasy, has finished its provisions and spun its cocoon wherein to sleep the slumber akin to death, the necessary period of preparation for its future life, these other enemies hasten to the nests whose fortifications are powerless against their hideously ingenious methods. Soon on the sleeper's body lies a nascent grub which feasts in all security on the luscious fare. The traitors who attack the larvae in their lethargy are three in number: an Anthrax, a Leucopsis and a microscopic dagger-wearer. (Monodontomerus cupreus. For this and the Anthrax, cf. "The Life of the Fly": chapters 2 and 3. The Leucopsis is a Hymenopteron, the essay upon whom forms the concluding chapter of the present volume.—Translator's Note.) Their story deserves to be told without reticence; and I shall tell it later. For the moment, I merely mention the names of the three exterminators.
The provisions are stolen, the egg is destroyed. The young grub dies of hunger, the larva is devoured. Is that all? Not yet. The worker must be exploited thoroughly, in her work as well as in her family. Here are some now who covet her dwelling. When the Mason is constructing a new edifice on a pebble, her almost constant presence is enough to keep the aspirants to free lodgings at a distance; her strength and vigilance overawe whoso would annex her masonry. If, in her absence, one greatly daring thinks of visiting the building, the owner soon appears upon the scene and ousts her with the most discouraging animosity. She has no need then to fear the entrance of unwelcome tenants while the house is new. But the Bee of the Pebbles also uses old dwellings for her laying, as long as they are not too much dilapidated. In the early stages of the work, neighbours compete for these with an eagerness which shows the value attached to them. Face to face, at times with their mandibles interlocked, now both rising into the air, now coming down again, then touching ground and rolling over each other, next flying up again, for hours on end they will wage battle for the property at issue.
A ready-made nest, a family heirloom which needs but a little restoring, is a precious thing for the Mason, ever sparing of her time. We find so many of the old homes repaired and restocked that I suspect the Bee of laying new foundations only when there are no secondhand nests to be had. To have the chambers of a dome occupied by a stranger therefore means a serious privation.
Now several Bees, however industrious in gathering honey, building party-walls and contriving receptacles for provisions, are less clever at preparing the resorts in which the cells are to be stacked. The abandoned chambers of the Chalicodoma, now larger than they were originally, through the addition of the hall of exit, are first-rate acquisitions for them. The great thing is to occupy these chambers first, for here possession is nine parts of the law. Once established, the Mason is not disturbed in her home, while she, in her turn, does not disturb the stranger who has settled down before her in an old nest, the patrimony of her family. The disinherited one leaves the Bohemian to enjoy the ruined manor in peace and goes to another pebble to establish herself at fresh expense.