572 



NATURAL HISTORY. 



suspend from the branches of trees. These nests have a comparatively smooth outer covering, with an 

 aperture at the bottom, through which the Wasps pass in and out. The species of Polybia, and nearly 

 allied genera, which are numerous in South America, produce a great variety of nests. Thus one species 

 (P. sedula) suspends its nest by two or three short stalks from the twig of a tree, and as comb after comb 

 is added the outer walls are carried down to unite and suspend the lower ones, so that the nest consists 



of a series of storeys, access to each of which is obtained by a 

 small aperture in the outer wall leading into the space between 

 two combs. Another (P. rejectd) builds its nest on the same general 

 principles as the last, but leaves no apertures in the side walls. 

 Instead of these access is obtained to the upper combs through 

 vacant spaces left in the centre of all except the first. Some 

 species of Polybia build their nests of earthy materials. The large 

 size of many of these nests demonstrates the great number of 

 individuals that live together in them. A nest of Polybia liliacea 

 in the Paris Museum measures about five feet in length. Tatua 

 morio, a common species in Cayenne, builds its nest on much the 

 same principle as Polybia rejecta, but the apertures for access to the 

 successive combs are placed on one side near the wall of the nest. 

 Other species of the genus Polybia build nests agreeing in general 

 construction, with those of our indigenous Wasps when attached 

 to trees ; others, again, build their successive combs upon a twig or 

 slender branch, which, passing through them, serves the purpose of 

 a series of uniting columns; whilst one species (Chartergus apicalis) 

 places each of its combs at the end of a short column springing 

 nearly at a right angle from the supporting branch. All these 

 nests have a protective covering. 



Although we have only been able to refer in general terms to 

 a few of the almost endless variety of beautiful structures made 

 by the social forms, we must pass on to the Solitary Wasps 

 (Eumenides), in which only true males and true females occur, and 

 which are distinguished from the preceding by their deeply-toothed 

 or bifid tarsal claws, and their generally long and slender mandibles. 

 These are usually considerably smaller than our ordinary Wasps, 

 but are nevertheless unmistakably wasp-like in aspect. They are 

 generally black, with the thorax more or less spotted and the 



abdomen ringed with yellow. The species are tolerably numerous and widely distributed. They 

 breed chiefly in holes, which the female makes in various situations, sandy banks, dead and decaying 

 wood, and old walls being preferred ; but some of them construct small nests of earthy materials in 

 which to deposit their eggs. The nests are generally furnished with a supply of insects or their larvae, 

 which the little freebooters ruthlessly seize and carry off for the sustenance of their offspring. 



One of the commonest and best known species is the Wall Wasp (Odynerus parietum), which 

 may be almost constantly seen haunting sunny walls during the months of June and July. It makes 

 its burrows in walls and clay banks, digging out with its mandibles a small hole which may be three or 

 four inches deep, and employing part of the materials removed in building outside the hole a tubular 

 passage leading to it, which at first projects straight from the wall, but towards the end bends 

 downwards. The object of this outwork may no doubt be to prevent the ingress of certain parasites, 

 especially the Gold Wasps (Chrysididse), which are incessantly prowling about with the object 

 of introducing their eggs into the nests of other Hymenoptera; but Dr. Taschenberg thinks that it is 

 simply for the purpose of having the materials at hand for the purpose of closing up the nest when 

 finished and stored. It may probably serve both purposes. The provisions carried into the nest 

 when completed consist of small larvae of Beetles or Lepidoptera. The insect grasps her booty with 

 her jaws near the head, holds it tinder her body by means of her legs, flies with it to the nest, and 

 conveys it to the further end of the cavity, where it is carefully packed away, curled into a ring-like 



POLISTES GALLICA AND NEST. 



