v SOCIAL HOMES 193 



like the floors of the Chartergus circular in plan, 

 but flat, and the union of each with the envelope 

 is absolutely perfect. The entrance, however, is en- 

 tirely lateral, and the insects gain admission to the 

 different tiers by very eccentric* holes. A nest well 

 in progress contains many combs. In one of the 

 kind the lower chambers are likely to be incom- 

 plete, since the floors are made before the cells are 

 built. The wasps seem always to be in readiness 

 for an emergency ; they build new stages ere they 

 require them, and lay the foundations of future cells. 

 The construction of the former is a long and toilsome 

 business, but the latter are quickly formed, and 

 eggs can be laid in cells that are just begun ; during 

 the development of the larvae there is abundance 

 of time to finish them. How many tiers are made 

 before cells are attached to them, or whether cells are 

 added as soon as the floors are completed are at 

 present moot points. Though at the beginning of 

 winter the nests are abandoned, they long resist the 

 severity of the season ; whether the societies are dis- 

 solved every year has not been ascertained. It is 

 equally uncertain if colonies take possession of desert- 

 ed nests or invariably build anew. Each comb may 

 serve for one laying, or may be cleansed and put to 

 further use. 



The genus Polybia is common in tropical America, 

 in the Asiatic Archipelago it occurs more sparingly 

 but is unknown in Europe. Some of the small homes, 

 as those of P. palmarum and sedula, generally consist 

 of a single comb of hexagonal cells on the surface of 

 a leaf, and clothed with a ceiling of somewhat frail 



O 



