The Pelopæus, for instance, builds her cells with earth already softened into mud. This is instinct. She has always built in this way. Neither the passing ages nor the struggle for life will induce her to imitate the Mason-bee and make her nest of dry dust and cement. This mud nest of hers needs a shelter against the rain. A hiding-place under a stone, perhaps, sufficed at first. But when she found something better she took possession of it. She installed herself in the home of man. This is discernment. She supplies her young with food in the form of Spiders. This is instinct, and nothing will ever persuade her that young Crickets are just as good. But should there be a lack of her favourite Cross Spider she will not leave her grubs unfed; she will bring them other Spiders. This is discernment. In this quality of discernment lies the possibility of future improvement for the insect. IV HER ORIGIN The Pelopæus sets us another problem. She seeks the warmth of our fireplaces. Her nest, built of soft mud which would be reduced to pulp by damp, must have a dry shelter. Heat is a necessity to her. Is it possible that she is a foreigner? Did she come, perhaps, from the shores of Africa, from the land of dates to the land of olives? It would be natural, in that case, that she should find our sunshine not warm enough for her, and should seek the artificial warmth of the fireside. This would explain her habits, so unlike those of the other Wasps, by all of whom mankind is avoided. What was her life before she became our guest? Where did she lodge before there were any houses? Where did she shelter her grubs before chimneys were thought of? Perhaps, when the early inhabitants of the hills near Sérignan were making weapons out of flints, scraping goatskins for clothes, and building huts of mud and branches, those huts were already frequented by the Pelopæus. Perhaps she built her nest in some bulging pot, shaped out of clay by the thumbs of our ancestors; or in the folds of the garments, the skins of the Wolf and the Bear. When she made her home on the rough walls of branches and clay, did she choose the nearest spot, I wonder, to the hole in the roof by which the smoke was let out? Though not equal to our chimneys it may have served at a pinch. If the Pelopæus really lived here with the earliest human inhabitants, what improvements she has seen! She too must have profited greatly by civilisation: she has turned man’s increasing comfort into her own. When the dwelling with a roof and a ceiling was planned, and the chimney with a flue was invented, we can imagine the chilly creature saying to herself: “How pleasant this is! Let us pitch our tent here.” But we will go back further still. Before huts existed, before the niche in the rut, before man himself had appeared, where did the Pelopæus build? The question does not stand alone. Where did the Swallow and the Sparrow build before there were windows and chimneys to build in?