134 TIMBERS AND THBIE USES 



is another inveterate tunneller of Oaks and 

 certain fruit trees. 



Certain of the Scolytidce have the ingenious 

 but injurious habit of growing moulds in their 

 tunnels with the object of feeding their larvae. 

 From the standpoint of bionomics these fungus- 

 growing beetles are of exceeding interest; from 

 the point of view of the forester, they are a 

 nuisance and worse, for the fungi often complete 

 the work of destruction started by the borings 

 of the beetles. 



There are many Lepidoptera which are wood 

 borers in their larval stages. An interesting 

 species is Dioryctria abietella, whose larvae bore 

 into the cones of Spruce and Silver Fir during 

 the late summer. Of aU the British Lepidoptera, 

 however, the palm for destructiveness must be 

 awarded to the Goat Moth, Cossits ligniperda. 

 By preference this insect is a pest of WUlows, 

 but it also attacks Elm, Ash, Poplar and Oak. 

 The large, heavy-bodied females are on the wing 

 in early summer and deposit their eggs upon 

 the trunk of some favoured tree. Directly the 

 larvae emerge, they bore directly through the 

 bark and into the wood of the tree. For three 

 years they contiaue to feed on the wood, boring 

 the while with their powerful jaws, assisted by 

 a fluid which they give ofi from their mouths 

 with the object of softening the wood. This 



