A first group of cells is established, we will suppose, at the bottom of a pit dug in virgin soil. The whole thing, cells and pit, is the work of one insect. When the moment comes to leave the underground dwelling, the Bees emerging from this nest will find before them an open road, or one at most obstructed by crumbly matter, which offers less resistance than the neighbouring soil, as yet untouched. The exit-way will therefore be the primitive way, contrived by the mother during the construction of the nest. All enter upon it without any hesitation, for the cells open straight on it. All, coming and going from the cells to the bottom of the shaft and from the shaft to the cells, will take part in the clearing, under the stimulus of the approaching deliverance.
It is quite unnecessary here to presume among these underground prisoners a concerted effort to liberate themselves more easily by working in common: each is thinking only of herself and invariably returns, after resting, to toil at the inevitable path, the path of least resistance, in short the passage once dug by the mother and now more or less blocked up.
Among the Cylindrical Halicti, any one who wishes emerges from her cell at her own hour, without waiting for the emergence of the others, because the cells, grouped in small stacks, have each their special outlet opening into the common gallery. The result of this arrangement is that all the inhabitants of one burrow are able to assist, each doing her share, in the clearing of the exit-shaft. When she feels fatigued, the worker retires to her undamaged cell and another succeeds her, impatient to get out rather than to help the first. At last the way is clear and the Halicti emerge. They disperse over the flowers around as long as the sun is hot; when the air cools, they go back to the burrows to spend the night there.
A few days pass and already the cares of egg-laying are at hand. The galleries have never been abandoned. The Bees have come to take refuge there on rainy or very windy days; most, if not all, have returned every evening at sunset, each doubtless making for her own cell, which is still intact and which is carefully impressed upon her memory. In a word, the Cylindrical Halictus does not lead a wandering life; she has a fixed residence.
A necessary consequence results from these settled habits: for the purpose of her laying, the Bee will adopt the identical burrow in which she was born. The entrance-gallery is ready therefore. Should it need to be carried deeper, to be pushed in new directions, the builder has but to extend it at will. The old cells even can serve again, if slightly restored.
Thus resuming possession of the native burrow in view of her offspring, the Bee, notwithstanding her instincts as a solitary worker, achieves an attempt at social life, because there is one entrance-door and one passage for the use of all the mothers returning to the original domicile. There is thus a semblance of collaboration without any real co-operation for the common weal.
Everything is reduced to a family inheritance shared equally among the heirs.
The number of these coheirs must soon be limited, for a too tumultuous traffic in the corridor would delay the work. Then fresh passages are opened inwards, often communicating with depths already excavated, so that the ground at last is perforated in every direction with an inextricable maze of winding tunnels.
The digging of the cells and the piercing of new galleries take place especially at night. A cone of fresh earth on top of the burrow bears evidence every morning to the overnight activity. It also shows by its volume that several navvies have taken part in the work, for it would be impossible for a single Halictus to extract from the ground, convey to the surface and heap up so large a stack of rubbish in so short a time.
At sunrise, when the fields around are still wet with dew, the Cylindrical Halictus leaves her underground passages and starts on her foraging. This is done without animation, perhaps because of the morning coolness. There is no joyous excitement, no humming above the burrows. The Bees come back again, flying low, silently and heavily, their hind-legs yellow with pollen; they alight on the earth-cone and at once dive down the vertical chimney. Others come up the pipe and go off to their harvesting.
This journeying to and fro for provisions continues until eight or nine in the morning. Then the heat begins to grow intense and is reflected by the wall; then also the path is once more frequented.
People pass at every moment, coming out of the house or elsewhence.
The soil is so much trodden under foot that the little mounds of refuse surrounding each burrow soon disappear and the site loses every sign of underground habitation.
All day long, the Halicti remain indoors. Withdrawing to the bottom of the galleries, they occupy themselves probably in making and polishing the cells. Next morning, new cones of rubbish appear, the result of the night's work, and the pollen-harvest is resumed for a few hours; then everything ceases again. And so the work goes on, suspended by day, renewed at night and in the morning hours, until completely finished.
The passages of the Cylindrical Halictus descend to a depth of some eight inches and branch into secondary corridors, each giving access to a set of cells. These number six or eight to each set and are ranged side by side, parallel with their main axis, which is almost horizontal. They are oval at the base and contracted at the neck.
Their length is nearly twenty millimetres (.78 inch.--Translator's Note.) and their greatest width eight. (.312 inch.--Translator's Note.) They do not consist simply of a cavity in the ground; on the contrary, they have their own walls, so that the group can be taken out in one piece, with a little precaution, and removed neatly from the earth in which it is contained.
