182 Bionomics o/ Cryplialus abietis 



sapvvood at all until about to pupate when they invariably cut a pit or 

 bed in the outer surface of the sapwood. This bed or pit excavated by 

 larvae about to pupate lies in no constant direction. Sometimes it may 

 be in the vertical direction, at other times horizontal, and at others 

 oblique. 



Thus when a piece of bark is removed from an infested branch the 

 brood galleries cannot be traced on the sapwood at all. As a rule one 

 can trace only that portion of the larval galleries which was cut previous 

 to pupation and the pupal bed or pit on the exposed wood surface. 

 While this is the typical occurrence other appearances are possible. 

 For example, in further observations I noticed that when the bark was 

 somewhat thick, as in the case of strong branches, the larval galleries 

 often did not groove the sapwood at all and usually on these branches 

 pupation took place in the bark. Where the bark was thin on the other 

 hand, as on twigs and on small branches, the larval galleries throughout 

 their entire length grooved the sapwood deeply while the pupal beds in 

 such places were very marked on the surface of the sapwood. As a 

 result when the outer bark was removed from an infested branch with 

 fairly thick bark only the pupal beds could be traced. While if this 

 same operation was performed on an infested twig or weak branch when 

 the bark was thin the larval galleries and pupal beds could easily be 

 traced on the wood surface. 



After the period of pupation has passed the young imagos first feed 

 on the patches of the inner bark which surround their pupal beds and 

 then finally bore to the outside through the bark and issue by the small 

 exit holes. 



As I point out later in this paper the parent beetles do not all die 

 after egg-laying but in many cases feed anew prior to a possible second 

 egg-laying. I have frequently found these old parent beetles after their 

 egg-laying has been completed cutting galleries which resembled in 

 shape and in direction larval ones. 



Irregular Galleries. 



Overcrowding of both mother and larval galleries is not uncommon 

 and takes place on badly infested stems and branches (Fig. 9) with the 

 result that the galleries may be very irregular both in shape and in 

 direction. In many cases it is extremely difficult or impossible to trace, 

 in the confused workings, individual galleries. As a rule on badly infested 

 branches the larval galleries are much shorter than those found on not 

 so badly attacked ones. As a common instance of overcrowding we 



