With these data let us try to explain the Ammophila swarm on the crest of Mont Ventoux. What could these numerous Hymenoptera under their sheltering stone have been about? Were they meaning to take up winter quarters there and await under their flat stone, benumbed, the season propitious to their labours? Everything points to the improbability of this. It is not in August, at the time of the greatest heat, that an animal is overcome with winter sleep. Want of their food—the honey juice sucked from flowers—cannot be suggested. September showers will soon come, and vegetation, suspended for a while by the heat of the dog days, will assume new vigour and cover the fields with a flowery carpet almost as varied as that of spring. This period—one of enjoyment for most of the Hymenoptera—cannot possibly be one of torpor for A. hirsuta. Again, can one suppose that the heights of Ventoux, swept by the gusty Mistral, uprooting beech and pine,—summits where the bise whirls about the snow for six months of the year,—crests wrapped for the greater part of the year by cold clouds and mist,—can be adopted as a winter refuge by such a sun-loving insect? One might as well make it hibernate among the ice fields of the North Cape! No, it is not there that A. hirsuta must pass the cold season. The group observed there were making a temporary halt. At the first indication of rain, which, though it escaped us, could not escape the insect so eminently sensitive to the variations of the atmosphere, the wayfarers had taken refuge under a stone, and were waiting for the rain to pass before they resumed their flight. Whence came they? Where were they going? In this same month of August, and especially in September, there come to the warm olive region flocks of little migratory birds; descending by stages from the lands where they have loved,—fresher, more wooded, more peaceful lands than ours,—where they have brought up their broods. They come almost to a day in an invariable order, as if guided by the dates of an almanac known only to themselves. They sojourn for a while in our plains, where abound the insects which are the chief food of most of them; they visit every clod in our fields where the ploughshare has turned up innumerable worms in the furrows, and feast on them, and with this diet they speedily lay on fat,—a storehouse and reserve to serve as nutrition against toils to come, and thus well provided for the journey they go on southward, to reach winterless lands where insects are always to be found, such as Spain and Southern Italy, the isles of the Mediterranean and Africa. This is the season for the pleasure of shooting and for succulent roasts of small birds.