Page:Popular Science Monthly Volume 49.djvu/666

644 demolished on the spot or borne away. Wasps often attack butterflies of different kinds; pouncing upon the luckless victims, as a falcon on a bird, they drag them to the ground and mutilate them, and subsequently the mangled body seems to be robbed of all vitality ere the wasp takes its final departure with it to the nest. Curiously, if it misses its aim, it does not strike a second time, but flies on, as if to cover its defeat. Immoderately fond of honey, it frequents the vicinity of beehives, ready to swoop on the bees returning home charged with their hard-got spoil.

Social wasps have two principal modes of nidification. Either the combs are enveloped in a covering of simple leaves of generally slender paper, analogous to that which serves for the cells; or the covering is of cardboard, composed of only one layer of material, of a consistence at times extraordinarily thick and resisting, at others slight and supple.

The common paper-makers build in the open air, on trees or bushes, under the roofs of outbuildings, on a beam, or in some such situation; the construction corresponds with that of the ground wasps, but the texture of the foliaceous envelope, which is fabricated with perfect art, has all the appearance of shell-work. It incloses an infinity of cells arranged in many tiers. A nest is invariably built from above downward. The start is made by accumulating on the determined site a good supply of paper, forming it into an umbrellalike canopy. To the under side of this cap—the ceiling, so to speak—the first comb is attached, and the rest of the work consists in prolonging the canopy more or less in an egg-shape, and in establishing additional combs, free, as a rule, only pendent to columns of paper, which pass from the upper surface of each comb to the comb immediately above; entrance is obtained at the lower end. Toward the summit of the envelope is a thickened cellular mass, but this portion excepted, it is made up of a number of separate leaves or layers of paper, limited in size and imbricated, and in contact together merely at the points of imbrication, leaving large cellular spaces between the sheets; moreover, the points of fusion of two successive sheets never fall one over the other. Each sheet therefore lies on a stratum of air, with the result that the exterior layers may be soaked with rain without soiling in the least the ones beneath. Tree wasps increase the size of the combs by cutting away the inner layers of the envelope, taking care to add layers externally so as to maintain, and even to slightly augment, the thickness of the walls, in proportion to the greater magnitude now assumed by the edifice.

Some elegant and graceful pensile nests, although diverse in form, have this in common, that the combs are always destitute of any envelope; and the cell-group is supported by a stalk of paper.