INSECTA : HYMENOPTERA 



393 



inches across each way, and often have seven separate combs 

 with a space about \ an inch deep between the successive 

 layers. There may be altogether eight or nine thousand 

 cells, which means at least twice that number of wasps have 

 developed during the season, since each cell is used two or 



Fig. 303. — Section of the subterranean Nest of the Common Wasp 

 (after Janet). 



6, Root to which the first attachment of the nest was made ; c, secondary attachments ; 

 ml to m7, the layers of comb ; /, chief suspensory pillar of comb ; 7t, one of the 

 secondary pillars ; i, layers of wasp-paper forming the envelope round the nest ; 

 )t, entry to the nest ; g, lateral galleries ; j, vacant space round nest. 



three times. The outer envelope will have been enlarged, 

 and it now covers the whole structure with several layers of 

 " wasp-paper." These help to retain the warmth engendered 

 by the crowds of insects within and which is necessary for the 

 development of the brood. The average, temperature of the 

 nest is about 88° F., i.e. often many degrees above that of 

 the surrounding air or soil.^ 



1 See Janet and Guiot's observations quoted by 0. Latter. 



