THE JOURNAL 



OF THE 



BOARD OF AGRICULTURE. 



Vol. XIIL No. 7. 

 90TOBE^, 1906. 



THE LARGE LARCH SAWFLY. 

 {Nematus Eric/isoni.) 



The impDrtance of a careful outlook by the sylviculturist and 

 the arboriculturist in order to observe whether or no there seems 

 to be any increase above the normal of a special insect, receives 

 once more strong support in the recent ravages of larch, by the 

 caterpillars of the large larch sawfly over a large area in 

 Cumberland. We have in our country native species of forest 

 insects which once and again on the Continent or elsewhere 

 have been the cause of immense loss, and yet in Britain have 

 never attracted attention by any serious damage, or, indeed, by 

 any damage at all. There is always, however, the possibility 

 of danger to our trees from such species, and this danger 

 wi 1 grow with the increased area that may be put under forest 

 crops, and with the massing together of great numbers of the 

 trees of one species. 



Nematus E7'ichsoni is not a very common insect in Britain or 

 Europe generally. It is not even mentioned by name in the litera- 

 ture of wood or forest injury in Britain, and it is almost passed 

 over in the Continental forest literature as of little forest import- 

 ance. The increase, however, of this insect in the last three years 

 over a considerable area in Cumberland, and the damage done 

 by its larvae there, is a matter of great importance, and may 

 have, unless careful outlook be kept, grave results elsewhere. 

 It were a pity, after the loss and discouragement caused by 

 the larch canker fungus, if a second scourge in the shape of 

 this sawfly enemy should follow. Our foresters should be on 

 the alert against this possibility. The flood comes with a crack 

 in the dyke. The worst insect plagues in forestry have origin- 

 ated in a limited area, and wherever the principle of ''resisting 



T I 



