Spinning Caterpillars. 347 



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 import- 

 ance of such a precaution will appear more strikingly, when 

 we compare it with the instance formerly mentioned (page 

 215), in which only one ichneumon had been able to force 

 its way out, (J. R.) 



Nest of Puss-moth, inclosing five cocoons of au Ichneumon. Natural size. 



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 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 45, 

 46.) When it had completed its growth, it began to spin, 

 but in a very awkward manner attaching threads, as if at 

 random, to the bits of pollen which remained undevoured, 

 and afterwards tumbling about to another part of the box, as 

 if dissatisfied with what it had done. It sometimes perse- 

 vered to spin in one place till it had formed a little vaulted 



