INSECT PESTS OF TIMBER 121 



harmful is the Beech leaf miner, Orchestes jagi, 

 a pest of the Common Beech. The damage done 

 by this insect " gives the tree the appearance 

 of having sufiered severely from late spring 

 frosts. In fact, even practical men often 

 erroneously attribute the injuries to frost." The 

 female lays her eggs in the midrib of a Beech 

 leaf, at about its centre, and in less than a fort- 

 night the larvae hatch and at once eat their way 

 to the margin of the leaf, following the direction 

 of a side vein. Then the larvae continue to feed 

 on the substance of the leaf, between the upper 

 and lower skins, which they leave intact, thereby 

 causing a large bhster. In less than three weeks 

 they are fully fed and pupate within the leaf 

 tissues. In another fortnight the adults appear 

 and continue the evil work of their immature 

 days by eating countless holes in the leaves. 

 Winter is passed in a state of hibernation in the 

 adult stage. 



Of the leaf-eating Hymenoptera, by far the 

 most destructive are the Sawflies, of which the 

 Pine Sawfly, Lophyrus pini, may serve as an 

 example. This insect, in its larval stage, is very 

 destructive to Northern Pines. In the spring 

 the females lay their eggs in the young Pine 

 leaves. Each female is armed with a sawlike 

 organ, with which she cuts a hole in the leaf 

 and deposits her egg therein. In a fortnight or 



