364 The Trees of Great Britain and Iceland 



that many will not survive. In the nursery I have observed that some trees were 

 practically immune, though growing side by side with others whose branches touched 

 them and were covered with the Chermes ; but having marked these trees and 

 watched them after they were planted out, I have not as yet been able to assure 

 myself that this immunity is permanent. Though I have not found this insect 

 attack Japanese, American, and Siberian larches at Colesborne as severely as 

 the common species, yet I have seen it upon them all, both there and elsewhere, 

 Blandford ' says that washing the trees in April with a soft soap and paraffin mixture 

 in hot water may prove effective, and suggests other forms of wash ; yet it is evident 

 that such remedies cannot be economically employed in plantations, and I know of 

 no means of preventing the ravages of this insect ; though thin planting, mixing with 

 hardwoods, and the avoidance of thin dry soils and damp shady situations are 

 undoubtedly the best means of avoiding severe injury from this pest, as well as 

 Peziza. 



Leaf-Miner of the Larch? The only other insect that I know of which causes 

 serious injury to larch in this country is a small tineid moth, Coleophora laricella. 

 This is extremely prevalent almost every year in some of my own plantations 

 having a south-west aspect, and has been supposed by some authors to be directly 

 connected with the attacks of Peziza, which usually accompany or succeed it. 

 According to Stainton the larva is hatched in the autumn, and at first feeds as a 

 miner inside the leaves, and at the approach of winter retires to the stem of the tree, 

 where it passes the winter without feeding. In the spring as soon as the leaves 

 appear it begins to work, and frequently becomes so numerous that most of the buds 

 have several leaves injured. In May it is fully fed, and attaches the case which it 

 has formed for itself from the leaves of the tree to a twig, and appears as a perfect 

 insect in July. The tree is undoubtedly very much weakened by severe and 

 repeated attacks, which render it more liable to die from Peziza, but as far as I know 

 there is no practicable remedy for it in plantations. 



A new enemy to the larch which has recently appeared in the north of England 

 was described in i\i& Journal of the Board of Agriculture in 1906, p. 375, and more 

 fully in a paper by Mr. J. Smith Hill.^ This is the larva of a sawfly, Nematus 

 Erichsonii, Hartig, which was first noticed about 1904 by Mr. Cyril F. Watson, of 

 Cockermouth, and which has done considerable damage in the Lake district of 

 Cumberland by defoliating the larch. Mr. Gillanders has recently found the larva 

 near Rothbury, and Mr. Forbes in Chopwell woods, but I have not heard of its 

 appearance in the south of England. 



I am informed by Mr. R. D. Marshall, of Castlerigg Manor, that he has known 

 periodical visitations of the same insect for several years, and that, owing to the late 

 period of the season at which the larva appears, the trees have not suffered as seriously 

 as they would if attacked earlier. He states that the plantation alluded to by Mr. 

 Smith Hill first suffered from this cause as much as forty years ago, and has survived 

 the attack in three consecutive years recently. It was noticed that during these 



' Journ. Roy. Hort. Sac. 1892, p. 170. ^ q{ Card. Chron. xxxvi. 181, figs. 70, 71 (1 904). 



3 Qitarterly Journal of Forestry, i. p. 67 (1907). 



