It is plain, then, that even if the young Pelopæus were not so chilly by nature, a shelter is indispensable for the nests, which would go to pieces at the first shower of rain. That is why this Wasp is so fond of human dwellings, and especially of the chimney. Before receiving its final coating, which covers up the details of the building, the nest has a certain beauty of its own. It consists of a cluster of cells, sometimes arranged side by side in a row—which makes it look rather like a mouth-organ—but more often grouped in layers placed one above the other. I have sometimes counted as many as fifteen cells; some nests contain only ten; others are reduced to three or four, or even only one. In shape the cells are not far from cylinders, slightly larger at the mouth than at the base. They are a little more than an inch long, and about half an inch wide. Their delicate surface is carefully polished, and shows a series of string-like projections, running cross-wise, not unlike the twisted cords of some kinds of gold-lace. Each of these strings is a layer of the building; it comes from the clod of mud used for the coping of the part already built. By counting them you can tell how many journeys the Wasp has made in the course of her work. There are usually between fifteen and twenty. For one cell, therefore, the industrious builder fetches materials something like twenty times. The mouth of the cells is, of course, always turned upwards. A pot cannot hold its contents if it be upside down. And the Wasp’s cell is nothing but a pot intended to hold the store of food, a pile of small Spiders. The cells—built one by one, stuffed full of Spiders, and closed as the eggs are laid—preserve their pretty appearance until the cluster is considered large enough. Then, to strengthen her work, the Wasp covers the whole with a casing, as a protection and defence. She lays on the plaster without stint and without art, giving it none of the delicate finishing-touches which she lavishes on the cells. The mud is applied just as it is brought, and merely spread with a few careless strokes. The beauties of the building all disappear under this ugly husk. In this final state the nest is like a great splash of mud, flung against the wall by accident. III HER PROVISIONS Now that we know what the provision-jar is like, we must find out what it contains. The young Pelopæus is fed on Spiders. The food does not lack variety, even in the same nest and the same cell, for any Spider may form a meal, as long as it is not too large for the jar. The Cross Spider, with three crosses of white dots on her back, is the dish that occurs oftenest. I think the reason for this is simply that the Wasp does not go far from home in her hunting-trips, and the Spider with the crosses is the easiest to find.