142 TREE WOUNDS AND DISEASES 



The tree wasp or giant sirex (Sirex gigas) is 

 one of the most persistent and injurious of 

 boring insects, attacking the Scotch pine and 

 sometimes the larch. It is a beautiful insect, 

 i^ inch long, of a black colour relieved by 

 golden bands. Generally, too, felled trees, or 

 such as are somewhat sickly, are chosen by 

 the female in which to lay her eggs. These 

 are deposited beneath the bark by means of 

 the powerful ovipositor, and in course of time 

 the whitish cylindrical maggots make their 

 appearance. The maggots feed in the solid 

 wood, making holes that are about a quarter 

 of an inch in diameter by means of their 

 powerful jaws. We have known not only the 

 Scotch pine and spruce to be attacked by this 

 formidable insect, but quite a number of larch 

 planks were forwarded to us from northern 

 England that were rendered worthless as timber 

 owing to the attacks of the giant sirex. Pre- 

 vention is better than cure in dealing with 

 this insect, and fallen and felled trees should 

 be removed from the woodlands as quickly as 

 possible. Weakly or damaged trees and old 

 stumps should also be dealt with. The tree 



