196 



Bionomics of Cryplialus abietis 



borings 



This is remarkable as a number of males and females were 

 working together. The dissection of the reproductive organs of a number 

 of these beetles on November 29th, 1917, and up to December 3rd, 1917, 

 however showed that although they had been feeding for some time the 

 reproductive organs were not ready for egg-laying. 



ARE TWO BROODS IN THE RELATIONSHIP OF BROTHERS 

 AND SISTERS POSSIBLE IN A YEAR? 



My observations show that when the parent beetles have bred and 

 their brood gallery is completed sometimes the male dies before the 

 female has laid her last egg, the female beetle surviving. Very frequently 

 the females die immediately after laying is completed and in many cases 

 the males survive. In some cases both parents die, in others both survive 

 after a first breeding. The mortality amongst parents that have already 

 bred is considerable. Those survivors, male or female, tunnel galleries of 

 a much similar appearance to those of the larval ones and feed on the 

 gnawed material, obtaining nourishment from it and so recuperate their 

 reproductive organs for a possible second egg-laying. 



In my experiments a number of parent beetles that had completed 

 egg-laying in the end of June, 1917, tunnelled and fed. The results of 

 these experiments are showai in Table II. 



Table II. 



HOST TREES. 



From observations made in the field I find that C. ahietis confines 

 itself in Scotland to breeding on the stems, branches and twigs of 

 unhealthy, dying, or dead trees of three closely allied genera of conifers, 

 namely, Abies, Picea, and Pseudotsuga. Like many other injurious 

 insects C. ahietis has a preference for certain genera and species, but if 

 these are found wanting, deficient or in an unsuitable state for brood 

 purposes others may be chosen. 



My experience in Aberdeenshire, Kincardineshire and Midlothian 

 leaves me with no doubt that C. ahietis prefers, in Scotland at least, the 



