MASON-ANTS. 225 



and thus free from the calls of hunger. The preceding 

 month of Februarj^ and part of January, had been re- 

 markably severe; the frost had penetrated deep into the 

 earth, and long held it frozen ; the ants were in many cases 

 not more than four inches beneath the surface, and must 

 have been enclosed in a mass of frozen soil for a long 

 period ; yet they, their young, and the onisci, vi^ere per- 

 fectly uninjured by it : affording another proof of the 

 fallacy of the commonly received opinion, that cold is 

 universally destructive to insect life." * 



The earth employed by mason-ants is usually moist clay, 

 either dug from the interior parts of their city, or moist- 

 ened by rain. The mining-ants and the ash-coloured 

 (Formica fusca) employ earth which is probably not selected 

 with so much care, for it forms a much coarser mortar 

 than what we see used in the structure of the yellow ants 

 (F. flava) and the brown ants (F. hruanea). We have 

 never observed them bringing their building materials of 

 this kind from a distance, like the mason-bees and like the 

 wood or hill ant (^F. rufa) ; but they take care, before they 

 fix upon a locality, that it shall produce them all that they 

 require. We are indebted to Huber the younger for the 

 most complete account which has hitherto been given of 

 these operations, of which details we shall make free use. 



" To form," says this shrewd observer, " a correct judg- 

 ment of the interior arrangement or distribution of an ant- 

 hill, it is necessary to select such as have not been acci- 

 dentally spoiled, or whose form has not been too much 

 altered by local circumstances ; a slight attention will 

 then suffice to show that the habitations of the different 

 species are not all constructed after the same sj'stem. 

 Thus, the hillock raised by the ash-coloured ants will 

 always present thick walls, fabricated with coarse earth, 

 well-marked stories, and large chambers, with vaulted 

 ceilings, resting upon a solid base. We never observe 

 roads, or galleries, properly so called, but large passages, 

 of an oval form, and all around considerable cavities and 



* Journal of a Natiu-alist, p. 304. 



