644 POPULAR SCIENCE MONTHLY. 



demolislied on the spot or borne away. "Wasps often attack but- 

 terflies 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 gen- 

 erally 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 re- 

 sisting, 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 ; en- 

 trance 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. 



