Earth-Mason Caterpillars. 



221 



in the earth, the cavity would be a long tube fitted exactly 

 to its body (Fig. c) : it is essentially different. 



Nests, &c., of an Earth-mason Caterpillar. 



It does not indeed require very minute observation to 

 perceive that every grain of earth in the structure is united 

 to the contiguous grains by threads of silk ; and that conse- 

 quently, instead of the whole having been done at once, it 

 must have required very considerable time and labour. 

 This construction is rendered more obvious by throwing one 

 of these earthen cases into water, which dissolves the earth, 

 but does not act on the silk which binds it together. To 

 understand how this is performed, it may not be uninterest- 

 ing to follow the little mason from the beginning of his 

 task. 



When one of those burrowing caterpillars has done feed- 

 ing, it enters the earth to the depth of several inches, till 

 it finds mould fit for its purpose. Having nowhere to throw 

 the earth which it may dig out, the only means in its power 



