The cells which compose the nest, and which are to receive the larvæ of the insect, are of an oval shape, and of a pale yellow or even of a blackish colour. Fig. 334 represents these cells. The wax of which they are composed has none of the qualities of that of hive bees, but is soft, sticky, and brownish. [Illustration: Fig. 334.--Cells from a Humble Bee's nest.] When the mother humble bee--which at first was alone and built her house single-handed--has made a certain number of cells, she seeks for honey and pollen, and prepares a paste, which she deposits in the future cradles. She then lays six or seven eggs in each. The larvæ which come from them live in common, at the same table, under the same tent. The cell is at first only the size of a pea; it soon becomes too narrow, splits and cracks, and requires to be enlarged and repaired many times, a work of which our industrious insects acquit themselves with a good deal of care and attention. Before passing into the pupa state each larva spins for itself a shell or cocoon of very fine white silk. It ceases to eat, remains at first rolled up, then expands itself little by little, and changes its skin after three days. It passes fifteen days in the pupa state in a quiescent condition. After the normal time has elapsed for it to remain in its hiding-place, it delivers itself from its mummy-like covering, with the help of the mother or the workers. The humble bee then appears, robust, and its body covered with a greyish down. When the successive hatchings have furnished to the mother the reinforcement she is waiting for, the workers she has raised occupy themselves in building new cells, and in raising the wall of enclosure which is to protect the nest. This wall, formed of wax, starts from the base, and raises itself, like a vertical rampart, from every point in the circumference. They then surmount this by the first roof, which is flat, supported by some pillars, and in which they have left one or two irregular openings. The whole is finally protected by a hemispherical covering of moss, made into a sort of felt and lined with wax. Fig. 335 represents, in its entirety, a nest of this humble bee. [Illustration: Fig. 335.--Nest of the Moss Humble Bee (_Bombus muscorum_).] The workers also take their part in rearing the eggs. They bring the paste, which they slip into the cells to the larvæ by a small hole, which is shut immediately afterwards. Later, they again give their assistance in disengaging the pupæ from their envelopes. In short, they make themselves generally useful; but they have one bad fault: they are very fond of eating the eggs laid by the mother. They try to seize them as she deposits them, or drag them from the cells, and suck their contents. And so the mother is obliged to be incessantly defending her eggs against the voracity of the workers, and to be constantly on her guard, so as to be ready to drive away these marauders from cells newly filled.