The fierce Hornet (Vespa crabo, Linn.), chief of the Wasp clan by virtue of her strength and her warlike audacity, conforms to the same principles of the globular configuration and of air imprisoned between partition-walls. In the cavernous hollow of a willow or in the recesses of some empty granary, she manufactures a yellow, striped, very brittle cardboard, composed of an agglomeration of woody fragments. Her spherical nest is wrapped in an enclosure of broad convex scales, a sort of tiles which, welded to one another and arranged in multiple layers, leave between them wide intervals in which the air is held motionless. To employ an athermous substance such as air, in order to check the loss of heat; to anticipate our manufacturers of eiderdown quilts; to give the containing walls of the nest the shape that encloses the greatest capacity within the smallest wrapper; to adopt as a cell the hexagonal prism, which economizes space and material; these are scientific actions that accord with the data of our physics and geometry. We are told that the Wasp, proceeding from improvement to improvement, worked out her sensible building for herself. I cannot believe this when I see the whole nest perish, a victim to my tricks, which would easily have been baffled if the insect possessed the least power of reflection. These wonderful architects amaze us by their stupidity in the presence of a trifling difficulty. Outside their work of the moment there is a complete absence of all lucidity such as the progressive invention of the nest would demand. Of the various tests that assure me of this, I will mention the following, which is easily made. The Common Wasp has chanced to set up her dwelling in the enclosure. The establishment is beside one of the walks. No member of the household dares venture in that part; it would be dangerous to go near it. We must rid ourselves of these bad neighbours, who terrify the children. It will also be a good thing to profit by this excellent opportunity of experimenting with appliances which could not be used in the open fields, where the little country bumpkins would soon smash my glass to bits. All that is required is a large chemist’s bell-glass. At night, when all is dark and the Wasps have gone home, I place it over the entrance of the burrow, after first flattening the soil. To-morrow, when the Wasps resume their labours and find themselves checked in their flight, will they succeed in contriving a passage under the rim of the bell-glass? Will these sturdy workers, who are capable of digging a spacious cavern, realize that a very short subterranean tunnel will set them free? That is the question.