W. KiTCHlE 



183 



may take the case figured here, where the bases of two branches of the 

 same whorl have each been girdled bv mother galleries. Here the larval 



Fig. 9. Piece of branch of Silver Fir with irregular brood galleries of C. abietis due to 

 overcrowding. A side view is shown of the bases of two small branches which have 

 been girdled by mother galleries — represented in the figure as dark projecting portions 

 one on each side of the main branch. Note how the larval galleries arising from the 

 mother galleries have intermingled and so have completely girdled the main branch. 

 The original shape of the mother galleries is here obHterated completely by young 

 larval galleries (dark patches on the main branch) running together; later the larval 

 galleries separate, running upwards and downwards on the main branch. 



galleries which arise from each set of mother galleries usually inter- 

 mingle and as a result completely girdle the main branch. Further in 

 such cases (see figure) it is quite impossible to determine from which set 

 of mother galleries the larval ones arise. 



Even more confused workings than the above example are quite 

 common. For instance, where two or more females have chosen the 

 same axil of the branch or twig for brood purposes, the entrance holes 

 of the mother galleries are verv near to one another, which leads to 



