1906.] 



Tx4E Large Larch Sawfly. 



387 



enormous damage to larch in the summer of 1884 in and near 

 Quebec by the caterpillars. 



Defoliation of Larch in England. — During the past summer 

 the caterpillars of N. Erichsoni have been at work in very 

 large numbers over a considerable area in Cumberland. The 

 trees cover the mountain up to an elevation of i,6oo feet. 

 Part of the area is made up of pure larch, which suffered more 

 than another portion of the wood where the larch is mixed 

 with oak and a few other broad-leaved species. The attack 

 was first observed in 1904 ; it was more serious with the spread 

 of the insect in 1905 ; and again in the summer just past great 

 havoc was done. Caterpillars were sent to the Board of Agri- 

 culture and Fisheries for determination and report in August 

 of this year, and a visit to the affected district followed. 



The worst infested area, known as Dodd Wood, is on Miss 

 Spedding's Merehouse Estate, and is situated about four miles 

 from Keswick in the Bassenthwaite direction. In shape the 

 Dodd Wood is somewhat conical, hence is exposed to all points 

 of the compass ; the largest part, however, faces south. The 

 age of the trees attacked varies from twenty years to seventy 

 years and over, and the fact of tall trees being attacked adds 

 greatly to the difficulty of satisfactorily combating the cater- 

 pillars and the adult sawflies. When I visited the place in the 

 last week of August, the browned and withered appearance of 

 many of the trees attested the severity of the infestation. At 

 some hundreds of yards distance, looking up at the wood, the 

 eye could easily pick out the defoliated trees. Some of them 

 were practically in their winter condition, devoid of leaves- 

 Others which had been defoliated in July had by mid-August 

 started to produce new leaves, so that on inspection at the end 

 of August such larches looked as they normally do in April or 

 May, with the dwarf shoots bearing tufts or clusters of partly 

 grown leaves. 



Some seventy-year-old larches felled at the end of July and 

 the beginning of August had thousands of the sawfly cater- 

 pillars on them. These caterpillars, many of them dislodged 

 by the fall of the tree, made their way to the trees standing 

 near and attempted to ascend them, the bases of the trunks of 

 several hawthorns, for example, being hidden by their numbers. 

 The caterpillars, numerous and easy to find on the trees up to 



112 



