184 



Bionomics of Cryplialiis abietis 



great confusion of motlier galleries and larval galleries. The galleries 

 in such cases intersect each other in all directions, forming a network 

 underneath the outer bark layer. 



Again where the bases of branches of a whorl have already been 

 badly infested by beetles other parent beetles may commence boring 

 brood galleries on the main branch between the whorls. This occurrence 

 is very common on badly infested stems and branches and leads to 

 still greater confusion of brood galleries. 



An exceptional irregularity was found where a number of males 

 and females had used the same entrance hole from which to bore their 

 galleries. Each pair of parent beetles entered underneath the bark by 

 this common entrance hole and immediately proceeded to make a 

 separate mother gallery. These mother galleries radiated out in all 

 directions from the common entrance burrow (see Fig. 10). 1 have taken 

 as many as five pairs of beetles from such a set of galleries. 



Fig. 10. Irregular mother galleries (not finisheil) on a piece of Silver Fir stem. 



In dealing with the brood galleries of C. abietis it is quite impossible 

 in most cases to trace either mother or larval galleries on the removal of 

 the outer bark. 



