Page:Popular Science Monthly Volume 7.djvu/676

656 all this and much more which I cannot stop to recapitulate. You are also doubtless familiar with the still more wonderfully organized communities of ants, with their queens, their domestic laborers, and their warriors. You have heard of, if you have not watched, their marauding excursions, their fierce but well-ordered battles, the triumphal return of the victors laden with spoil, and with captives whom they reduce to the condition of domestic servants. I barely mention these examples because they are familiar to all, but I must describe more fully one case of instinct from the same family, which is probably less familiar to you and yet no less wonderful: I refer to the case of the common mud-wasp or clay-dauber.

These insects do not form organized communities, and therefore have no neuters or workers, but each female works for herself. Neither does she feed her young as do bees and other wasps, but provides appropriate food in abundance, and leaves them to themselves. But the mode of building her cells and supplying the appropriate food exhibits a marvelous wisdom. She gathers wet clay in pellets about the size of a duck-shot and commences to build. Going and coming from her clay-quarry to her work, with great patience, industry, and skill, she builds two or three cells side by side, two or three inches long and about half an inch in diameter. When finished she proceeds to fill them with food. For this purpose she attacks all varieties of spiders, stings them, plunging her sting with the greatest precision directly into the principal nerve-ganglion, and, after laying an egg in the body of each, carries them off and packs them away in the cells, until these are completely full, then seals them with clay and leaves them. In due time the eggs are hatched, the larvae feed upon the spiders, until they become perfect insects, and cut their way out of the cells.

Observe, then, first, the walls of the cells must be thin and composed of porous materials, otherwise the eggs could not hatch, nor the larvæ continue to live, for want of oxygen; second, the spiders must be helpless but not dead. If they were dead they would decompose or else dry up before they could be used as food. If, on the other hand, they were alive and active, they would destroy each other, and the contained eggs, and perhaps escape from the cell. But the poison is so adjusted as to quantity, and probably as to the place of insertion, as to produce a state of complete helplessness, a deep and permanent coma: the spiders are as it were chloroformed by the poison. If touched or irritated, they move only enough to show that they are not dead. As a boy I have many times watched these wasps gathering their materials, building their cells, gathering their food-supply of spiders. I have many times broken open their finished cells and found them full of spiders in the condition described. If one desires to study spiders, he can gather more varieties in one day, by breaking open the cells of mud-wasps, than in a year in any other way.