326 INSECT ARCHITECTURE. 



like the carbonized rootlets of a tree than silk, and 

 resembling in texture a piece of coarse milled cloth 

 or felt, such as is used for the bases of platted hats. 

 It is worthy of remark, that all these cells opened 



Nest of Putt-Moth, inclosing fine cocoons of an Ichneumon, 

 Natural size. 



towards one end, as if the caterpillars which con- 

 structed them had been aware that the wall of the 

 puss-moth, in which the flies would have to make a 

 breach, was very hard, and would require their 

 united efforts to effect an escape. The importance 

 of such a precaution will appear more strikingly, 

 when we compare it with the instance formerly men- 

 tioned (page 195), in which only one ichneumon 

 had been able to force its way out.* 



It appears indispensable to some grubs to be con 

 fined within a certain space, in order to construct 

 their cocoons. We saw this well exemplified in the 

 instance of a grub of one of the mason-bees (Omnia 

 bicornis), which we took from its nest, and put into 

 a box, with the pollen paste which the mother-bee 

 had provided for its subsistence. (See pages 40, 41.) 



