86 Insect Architecture. 



race are careful to proportion the thickness, and consequently 

 the strength of the walls to the magnitude of the building 

 designed to be erected. 



" The other method consists in forming hollow pieces, or 

 raising, as it were, blisters all over the plain surface which 

 the queen has left ; and upon these other blisters, and so on 

 continually ; cutting away, as in the former case, the under 

 skin on the formation of the outer one. The latter method 

 is adopted by the workers of V. crabro, V. vulgaris, and V. 

 germanica; the former by V. Norvegica, V. sylvestris, V. 

 rufa, and probably by V. arborea. Cutting away the inner 

 portions of the coverings is a necessary process in order to 

 make room for the increased size of the comb or combs. The 

 material cut away is not thrown by as. useless, but is worked 

 up afresh ; indeed this is effected in, and by, the very act of 

 removing it ; it is then either used in enlarging the combs or 

 it is brought out and employed in making additions to the 

 outside. 



" As the nest increases in size, it is obvious that the cavity 

 in which it is placed must be proportionably enlarged ; ac- 

 cordingly, each wasp, as it emerges from the aperture, may 

 be observed to bring out with it a small lump of earth which 

 it has scraped from the walls of the chamber, care being 

 taken to keep a clear space of about a quarter of an inch 

 between the covering of the nest, and the walls of the 

 chamber. About the same space also occurs between the 

 combs, which are placed horizontally, with the mouth of the 

 cells downwards ; supporting columns or pillars being con- 

 structed at regular intervals so as to keep them at a proper 

 distance apart, thus allowing the insects room to pass 

 between them for the purpose of feeding the grubs. Support- 

 ing columns or pillars are also placed between the roof of 

 the chamber and the crown of the nest, connecting the one 

 with the other ; and these supports are constantly strength- 

 ened as the increasing weight of the nest renders such a 

 precaution necessary. 



" The material of which the wasps' nests are composed is a 

 sort of paper manufactured chiefly from wood by the insects 



