INSECT PESTS OF TIMBER 127 



Tlie Pelted Beech. Coccus, Cryptococcus fagi, 

 is one of the most destructive of all the British 

 scale insects. The colonies of the insects appear 

 like a white felt on the bark of the tree upon 

 which they live and at times they are as much 

 as half an inch in thickness, causing the eventual 

 peeling away of the bark and the death of the 

 tree. The Common Beech is the favoured food 

 plant of this scale and, curiously enough, the 

 Copper Beech is rarely attacked. The females 

 do not secrete a scale as do the female Mussel 

 Scales, nor do they transform their own bodies 

 into scales after the manner of the Brown Scale, 

 but they secrete a waxy, white cotton wool-like 

 substance, which forms a protection against rain. 

 Beneath the waxy wool, the female lives and 

 deposits her relatively large, pale yellow eggs 

 in the summer. They hatch in the following 

 spring and quickly develop into adult females. 



Of the AfhididcB, the most destructive to 

 timber trees belong to the genus Chermes. Of 

 the six common British species, Chermes ahietis 

 and C. strobilobius, form galls on the terminal 

 shoots of Spruce. Chermes picece forms a white 

 woolly growth on the leaves and stems of the 

 Silver Fir ; C. pini forms a similar growth on 

 leaves and stems of' Northern and Austrian 

 Pines ; C. corticalis attacks Weymouth Pines 



