284 IXSECT ARCHITECTURE. 



the original building, five empty cells of a black colour, 

 about an inch long, and a sixth of an inch in diameter ; 

 nearly cylindrical in form, but somewhat flattened ; vertical 



Xest of Puss-moth, inclosing five cocoons of an Iclmeumon. Xatural size. 



and parallel to one another, though slightly cui^ed on the 

 inner side. The cells are composed of strong and some- 

 v^hat coarse fibres, more 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 plated 

 hats. It is worthy of remark, that all these cells opened 

 towards one end, as if the caterpillars which constructed 

 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 lorecaution will appear 

 more strikingly, when we compare it with the instance 

 formerly mentioned (page 170), in which only one ichneu- 

 mon had been able to force its way out. (J. E.) 



It appears indispensable to some grubs to be confined 

 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 (^Osmia hicornis), 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 33, 34.) When it had completed its growth, it began 

 to spin, but in a very awkward manner — attaching threads, 



