THE LARGE LARCH SAWFLY. 43 
10. The Large Larch Sawfly (Nematus Erichsoni).' 
(With Coloured Plate.) 
By R. Stewart MacDouGa.t, M.A., D.Sc., Honorary Consulting 
Entomologist to the Society. 
The importance 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 will 
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. 
Lematus Erichsoni is not a very common insect in Britain or 
Europe generally. It is not even mentioned by name in the 
literature of wood or forest injury in Britain, and it is almost 
passed over in the Continental forest literature as of little forest 
importance. The increase, however, of this insect in the last 
three years over a considerable area in Cumberland, and the 
damage done by its larve 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 
originated in a limited area, and wherever the principle of 
“resisting the first advances” is neglected, a plague may follow 
which no man can cure. 
Previous History of N. Erichsoni.—There are references in the 
forest literature of the Continent to the larvz of the large larch 
1 Reproducéd from Zhe Journal of the Board of Agriculture for October 
1906, by permission of the Controller of His Majesty’s Stationery Office. 
