A swarm never comes out except on a fine day, or, to speak more accurately, at an hour of the day when the sun is shining, when the air is calm, and the sky clear. It is generally between ten o'clock in the morning and three o'clock in the afternoon. "We observed," says Francis Huber, "in a hive all the signs which are the fore-runners of a cast for a swarm--disorder and agitation--but a cloud passed before the sun, and quiet was restored to the hive; the bees thought no more of swarming. An hour after, the sun having shown itself again, the tumult recommenced, increased very rapidly, and the swarm set out on its journey."[90] [90] In general, bees very much dislike bad weather; when they are foraging in the country, the appearance of a single cloud before the sun causes them to return home precipitately. However, if the sky is uniformly dark and cloudy, and if there are not any sudden alternations of darkness and light, they are not easily alarmed, and the first drops of a gentle rain hardly drive them away from their hunting-ground. At the moment which precedes their exit, the buzzing increases in the hive. Some of the workers go out first, as if to ascertain the state of the atmosphere. The moment the queen has passed the threshold, the emigrants follow in a cloud behind her; in an instant the air is darkened with bees, which crowd together and form a thick cloud. The swarm rises, whirling round about in the air; it poises itself for a few minutes over the hive, to allow time to reconnoitre, and for the laggards to join, and then goes off at full speed. The queen does not make choice of the place where the company shall find shelter. When a branch of a tree has been selected by a certain number, they fix themselves on it. Many others follow them. When a great many have collected, the queen joins the throng, and brings in her train the rest of the troop. The group already formed becomes larger and larger every instant. Those which are still scattered about in the air hasten to join the majority, and very soon all together compose one solid mass or clump of bees clinging to each other by their legs. This cluster (Fig. 322) is sometimes spherical, sometimes pyramidal, and occasionally attains a weight of nine pounds, and may contain as many as 40,000 bees. From this moment, although they are uncovered, they remain still. In a quarter of an hour everything becomes quiet, and the bees cease to hover about the cluster more than round an ordinary hive. Now is the moment to take possession of the swarm in a hive prepared beforehand to receive it. If delayed too long, the troop flies off, and establishes itself in some natural cavity, as the hollow of a tree, &c. The bees then return to their wild state.