W. Ritchie 197 



genus Abies (Silver Fir family) for brood purposes, having a special 

 preference for the species Abies pectinata D.C. (Common Silver Fir). 

 I have also found Cryphalus breeding on Abies cephalonica Link. 

 (Grecian Silver Fir) while in my breeding experiments the same insect 

 readily took to Abies nordmanniana Spach. (Norman's Silver Fir), and 

 Abies pinsapo Boissier (Spanish Silver Fir). It has also been recorded in 

 Scotland on Abies nobilis Lindl., a North American species. It is possible 

 that all the species of the genus Abies may be used for brooding purposes 

 if in a suitable condition. 



Next in order of preference, C. ahielis takes the genus Picea (Spruce 

 family), Picea excelsa Link, or Norway Spruce being the host plant on 

 which I have found it. 



Last in order but by no means of least importance C. abietis may 

 choose for brood purposes the genus Pseudotsuga (Douglas Fir family). 

 I have found the insect breeding freely in Aberdeenshire on the sickly 

 branches of standing Douglas Firs, Pseudotsuga Douglasii Carr., the only 

 species of the genus planted in this country. 



We see then that C. abietis possesses a wide range of host trees, an 

 exceedingly important factor which would have to be reckoned with in 

 dealing with the control of the species. 



As far as my observations go I am convinced that C. abietis in most 

 cases only takes to the Spruce and Douglas Fir families when the pre- 

 ferred Silver Fir family is deficient or is in an unsuitable state for 

 brooding purposes. 



On the continent of Europe, according to Nusslin^ and other writers, 

 C. abietis is typically a Spruce species. Nusslin also states that, although 

 it prefers the species of the genus Picea it also takes the genus Abies 

 and occasionally the genus Pinus. Of the species of the genus Pinus he 

 states that it prefers Pinus sfrobus L. or Weymouth pine. 



Kaltenbach^ quoting Ratzeburg names the species as attacking 

 Pinus strobus and the dry branches of Silver Fir. EichhofE^ names as 

 host plants Spruce, Silver Fir and Pine. 



ECONOMIC IMPORTANCE OF C. ABIETIS IN SCOTTISH FORESTRY. 



Occasional references in the forest literature of Central Europe 

 indicate that C. abietis has been known to be harmful especially if in 

 numbers it attacked very young stems. 



1 Nusslin, Leitfaden der Forst Insektenkunde, 1905, pp. 201-2. 

 - Die Pflanzen-F einde aus der Classe der Insekten, p. 685. 

 * Die Europa'isclien Borkenknfer, by W. Eichhoff, p. 177. 



