TOMICUS CHALCOGRAPHUS. 



249 



their way out generally in July. The insect may hibernate 

 in the larval, pupal or imago stage ; the generation is usually 

 annual, sometimes twice in the year. 



T. chalcographus is much less rare in Great Britain than 

 T. typographic. It is, however, local and not usually common, 

 resembling in this respect many other insects that feed on the 

 spruce, which is not an indigenous tree. On the Continent it 

 generally accompanies the two preceding species. 



c. Relatwns to the Forest. 



This bark-beetle ordinarily attacks only the spruce. It has, 

 however, occasionally been found in silver-fir, larch and Scots 

 pine, and also on Weymouth, Cembran and mountain pines. 



Fig. 107. Stellate galleries of 

 T. chalcographus, L., with 

 egg-recesses, in spruce-bark. 

 (Natural size.} 



Fig. 108. Stellate galleries of T. chalcoyraphus, L., 

 on spruce sapwood, radiating from the pairing- 

 chambers^), b Knots. 

 (Natural size. ~) 



It is very fond of interrupted pole-woods about 40 years old ; 

 in the case of old trees it attacks only the branches and crown, 

 leaving the destruction of the bast of the stem to the larger 

 species. Exceptionally it may be found in 8 to 12-year-old 

 spruce thickets which have been attacked by fungi (Aecidium 

 abietinum, Alb. et Schw.). 



The breeding-galleries are of characteristic stellate form, 

 consisting of 4 to 7 slightly curved arms, which run trans- 

 versely rather than longitudinally, groove the sapwood and 

 spring from a pairing-chamber excavated in the outer part of 



