THE SILVER FIR. 479 



desirable should be preserved at any cost, have been saved 

 whenever attacked, by the same process as that resorted 

 to by Sir T. D. Lauder, viz., scrubbing the boles and 

 branches of the trees with a brush, or what is as effectual, 

 with wisps of coarse grass or hay ; the labour and ex- 

 pense attending such a remedy it is evident must neces- 

 sarily restrict its application to very narrow limits, and 

 could scarcely be resorted to where the tree is planted 

 in mass or with a view to profit. Trees in the highest 

 health and growing luxuriantly, seem to be attacked as 

 freely, or perhaps even more so, than those advancing 

 at a slower rate, and Ave are inclined to think that those 

 growing in a rich soil are sooner infected, and to a greater 

 extent, than such as are planted upon one of inferior 

 quality. In the immediate vicinity of the house at Twizell, 

 where the ground is good, the insect has proved very 

 destructive, and few trees have escaped an attack ; but 

 in some outer plantations, where the soil is inferior, having 

 the surface mould of a blackish moory quality, with a 

 clayey substratum, the Silver Firs, though strong, vigo- 

 rous, and in good health, and now twenty feet high, 

 have hitherto remained untouched. In many parts of 

 Scotland some of the finest specimens have been killed 

 by it. Sir T. D. Lauder remarks that this has been the 

 case with most of the trees at Relugas and Ballindallock, 

 in Morayshire, and also at Cullenhouse, Banffshire. In 

 Dumfriesshire we have seen the sad havoc it has com- 

 mitted, and in many parts of the north of England it 

 is proving equally fatal to the species. This insect seems 

 limited to the Silver Fir, as we have not recognized it 

 upon auy other of the Abietina. The young shoots of 

 the Silver Fir are also frequently infested with an aphis, 

 but its attacks seldom do any serious injury to the tree. 



