W. KiTCIlIE 1H7 



Diagram B. 



This diagram is for comparison with Diagram A showing the possible 

 development of the last laid eggs of the same beetles. 



Year Jan. Feb. March Apl. .May June July Aug. Sop. Oct. Nov. Dec. 



191() + + • 



1917 - - - - - OO ++ 



DiagrcDu C. 



Life-cycle found where the brood material was lying under dense 

 shade and hence summer temperature low — here whole of young brood 

 hibernates as larvae. 



Year Jan. Feb. March Apl. May June July Aug. Sep. Oct. Nov. Dec. 



1910 • + , , _ _ 



1917 - - - - - OO + + + ....:.... 

 Length of life-cycle, egg to adult, here is about 11^ months. 



Diagram D. 



Exceptional case in length of life-cycle — here brood material was of 

 poor quality and in dense shade. 

 Year Jan. Feb. March Apl. May June July Aug. Sep. Oct. Nov. Dec. 



1916 + . . - 



1917 -_----__ 



From the diagrams it will be seen that the length of the larval period 

 is extremely variable. In the typical life-cycle it is from 69 to 71 days, 

 whereas where the beetles hibernate as larvae it may be about 111 

 months or longer. 



Further, it is obvious that owing to this great variation in the length 

 of the life-cycle there is a great deal of overlapping of generations of 

 beetlss. 



LENGTH OF LIFE OF C. ABIETI8 AND THE NUMBER OF 

 GENERATIONS IN A YEAR. 



It is now recognised amongst workers on Curculionids and Scolytids 

 that many of these beetles may not only have a long individual life -but 

 that the newly issued young brood of beetles cannot proceed at once to 

 an efficient copulation followed by egg-laying. EichhofE and his school 

 believed the contrary. More recent workers however, including Von 

 Oppen, Nusslin, and MacDougall for Curculionidae, and Pauly, Nusslin 

 and Knock e and Fuchs for Scolytidae, proved that Eichhofl's view was 

 erroneous. 



