134 LETTERS ON ENTOMOLOGY. 
mason, and she pulls it to pieces to stop up the 
hole again. You may perhaps object that it would 
be as easy to lay it in a heap at once ; but no one 
will deny that order is better than confusion, 
and it is quite as little trouble to carry the par- 
ticles and arrange them regularly as to throw 
them down and have the greater trouble of 
picking them up again; besides it serves as a 
bulwark, for often when she is flying abroad, the 
ichneumon fly might deposit in the hole an egg, 
which would become the deadly enemy of hers, 
and while this fortress stands her absence can- 
not be so well ascertained. When the cell is 
finished, and the egg laid in it, the careful mother 
has next to supply food for the future maggot ; 
and as they are carnivorous, perhaps you would 
never guess how she provides for twelve or more 
days. When the hole is opened it is found full 
of green grubs, curled round and piled on each 
other, to the number of ten or twelve. Their 
backs are placed against the side of the hole ; 
and as they are pressed closely together, cannot 
move, though quite alive. These grubs are of 
an opaque green, and always of the same species 
in each nest, or rather den. The wasp-maggot 
is yellow, and increases in size as he eats his 
prey, which he does in the following manner : 
