EARTH-MASON CATERPILLARS. 203 



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 under- 

 stand 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 feeding, 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 of forming a cavity 

 is to press it with its body ; and, by turning round 

 and round for this purpose, an oblong hollow is soon 

 made. But were it left in this state, as Re'aumur 

 well remarks, though the vault might endure the 

 requisite time by the viscosity of the earth alone, 

 were no change to take place in its humidity, yet, as 

 a great number are wanted to hold out for six, eight, 

 and ten months, they require to be substantially built, 

 a mere lining of silk, therefore, would not be suffi- 

 cient, and it becomes necessary to have the walls 

 bound with silk to some thickness. 



When a caterpillar cannot find earth sufficiently 

 moist to bear kneading into the requisite consistence, 

 it has the means of moistening it with a fluid which 

 it ejects for the purpose ; and as soon as it has thus 

 prepared a small pellet of earth, it fits it into the wall 

 of the vault, and secures it with silk. As the little 

 mason, however, always works on the inside of the 

 building, it does not, at first view, appear in what 

 manner it can procure materials for making one or 

 two additional walls on the inside of the one fi rst built. 

 As the process takes place under ground, it is not 

 easy to discover the particulars, for the caterpillars 

 will not work in glazed boxes. The difficulty was 

 completely overcome by M. Re'aumur, in the instance 



