188 Bionomics of Cryphalii« abietis 



My own recent work' on the Scolytids Myelophilus piniperda Linn, 

 and Myelophilus minor Hart, has corroborated the view of these 

 later workers. From the results of the researches of these workers it 

 has also been definitely proved that a large number of forest insects 

 belonging to the Scolytids and the Curculionids do not die after pairing 

 and a first egg-laying, but that after a period of renewed feeding in order 

 to rfecuperate and to render their sexual organs once more functional, 

 it is possible for them to proceed to a second pairing and a second egg- 

 laying. Von Oppen and others also showed that the imago on its trans- 

 formation from the pupal condition might be quite unripe and unable 

 to proceed to an efficient copulation followed by egg-laying, and that 

 in such a case an intervening feeding period was necessary for the 

 reproductive organs to become mature. 



Further, the question of whether two broods in the relationship of 

 parents, children, and grandchildren are possible in a year is greatly 

 dependent on two things, viz. whether a preliminary feeding is necessary 

 before breeding and if this feeding period be short or long. If this feeding 

 period be short then a second brood in the year is possible, whereas if 

 the period is long a second brood is impossible. 



The proving of the facts is not an easy matter in the case of C. abietis 

 where the most of the feeding previous to exit for mating takes place 

 under the bark in the place where the insect has reached its imago stage. 

 As underneath the bark of an infested branch or stem it is possible to 

 find Cryphalus beetles that have already bred and beetles that have 

 just reached the imago stage and have not bred at all, the true facts 

 as to length of life, number of broods possible, and the generations 

 possible in a year can only be ascertained by a dissection and comparison 

 of the reproductive organs of new imagos, beetles ready to pair, beetles 

 that are laying eggs and beetles that have completed egg-laying. 



THE MALE REPRODUCTIVE ORGANS OF CRYPHALUS ABIETIS. 



Fig. 11 shows the male reproductive organs dissected out. These 

 comprise the testes, vasa deferentia, seminal vesicles, accessory glands, 

 common vas deferens or duct and the penis. The testes are translucent 

 glandular bodies and as usual one lies on either side of the abdomen 

 ventrally. These produce the spermatozoa. Each testis (T.) is made up 

 of two lobes somewhat circular in shape and closely united along their 

 inner surfaces. From the posterior or under side of each testis, a duct 



1 Trans, lioi/al Socicli/ Ediii. vol. Lii, Part 1, No. 10. 



