INTRODUCTION 



common, whilst in the Ash they are of so dark a shade of olive-green as 

 to appear almost black in the distance. 



INSECT PESTS 



The timber of trees in the living state is subject to attack from insect 

 larva?, two of the most common being those of the Goat Moth (Cossus ligni- 

 perda) and the Wood Leopard Moth (Zeuzera cesculi). The former is most 

 frequently associated with Willows, but is also partial to Oak, Lime, and 

 fruit trees, especially Apple, Pear, and Plum. The latter attacks Ash, Beech, 

 Birch, Elm, Walnut, and the before-mentioned fruit trees. 



The larvae of Wood Wasps, especially the Giant Sirex (Sirex gigas), often 

 bore into the Fir trees, and those of many beetles work havoc in the wood 

 of other trees. 



FUNGOID PESTS 



Among fungoid diseases which affect decay in timber, two of the best 

 known are the Canker Fungus {Nectria ditissima), which is common in Apple 

 trees, but also attacks Pear, Plum, Oak, Beech, Ash, &c, and the Larch 

 disease or Larch Canker, which probably owes its origin to the spores of 

 Peziza Wilkommii. 



AGE OF TREES 



In spite of their many enemies trees often attain great age, and though 

 it is impossible to accept the estimates that have been made by the older 

 naturalists, there is little doubt that individuals have remained in a flourishing 

 condition for over a thousand years. 



Tradition places the age of some of the Cedars of Lebanon at about 

 3000 years, and probably the Yew has attained as great an age. The speci- 

 mens at Fountains Abbey are believed to have been flourishing twelve cen- 



xi 



