The cause of a swarm leaving the stock-hive is, that the population has grown too large for it. Swarming is a provision of Nature for remedying the inconvenience of overcrowding, and is the method whereby the bees seek for space in which to increase their stores. By putting on "super-hives," the required relief may, in many cases, be given to them; but should the multiplication of stocks be desired, the bee-keeper will defer increasing the space until the swarm has issued forth. In May, when the spring has been fine, the queen-bee is very active in laying eggs, and the increase in a strong, healthy hive is so prodigious that emigration is necessary, or the bees would cease to work.
It is now a well-established fact that the old queen goes forth with the first swarm, preparation having been made to supply her place as soon as the bees determine upon the necessity of a division of their commonwealth. Thus the sovereignty of the old hive, after the first swarm has issued, devolves upon a young queen.
As soon as the swarm builds combs in its new abode, the emigrant-queen, being impregnated and her ovaries full, begins laying eggs in the cells, and thereby speedily multiplies the labourers of the new colony. Although there is now amongst apiarians no doubt that the old queen quits her home, there is no rule as to the composition of the swarm: old and young alike depart. Some show unmistakable signs of age by their ragged wings, others their extreme youth by their lighter colour; how they determine which shall stay and which shall go has not yet been ascertained. In preparation for flight, bees commence filling their honey bags, taking sufficient, it is said, for three days' sustenance. This store is needful, not only for food, but to enable the bees to commence the secretion of wax and the building of combs in their new domicile.
On the day of emigration, the weather must be fine, warm, and clear, with but little wind stirring; for the old queen, like a prudent matron, will not venture out unless the day is in every way favourable. Whilst her majesty hesitates, either for the reasons we have mentioned, or because the internal arrangements are not sufficiently matured, the bees will often fly about or hang in clusters at the entrance of the hive for two or three days and nights together, all labour meanwhile being suspended. The agitation of the little folk is well described by Evans:—
"See where, with hurried step, the impassioned throng
Pace o'er the hive, and seem, with plaintive song,
T' invite the loitering queen; now range the floor,
And hang in cluster'd columns from the door;
Or now in restless rings around they fly,
Nor spoil thy sip, nor load the hollowed thigh;