[ 453 J 



LXXIII. On the Effects of anointing the Stems and Branches 

 of Fruit Trees with Oil, and on the means of destroying In- 

 sects. By Sir G. S. Mackenzie, Bart. * 



A HE trees in my garden having been much infested witli insects 

 in the vear 1815, 1 became anxious to devise memis to prevent 

 their increase. I recollected to have seen an apple tree in the 

 Duke of Buccleuch's garden at Dalkeith, which had been al- 

 most destroyed by what is called the scaly insect f ; but which 

 had recovered on the application of a mixture of oil, sulphur, 

 and soot. It is well known, that oil is fatal to insects, and to 

 this part of the mixture I attributed the recovery of the tree. I 

 conceived that oil, applied to the stems and branches of trees, 

 might act in two ways ; it might destroy the eggs and pupae of 

 insects already deposited ; and it might prevent the attack of in- 

 sects in future. It occurred to me also, that oil, by softening 

 hard and diseased portions of the bark, might be in these re- 

 spects beneficial to the health and growth of the tree, and ena- 

 ble the vegetative power to throw off such portions by a natural 

 process, which might be preferable to the more violent proceed- 

 ings of scraping, while the bark is constricted. 



With these views, I directed my gardener to anoint a con- 

 siderable number of trees of different kinds. Not being aware 

 of any injury which was likely to arise from allowing the oil to 

 touch the buds, he zealously rubbed every recess into which it 

 was possible for eggs to be deposited ; and this has been the 

 means of my discovering, more extensively than I should other- 

 wise have done, the effects of oil, both in regard to benefit and 

 injury ; though those of the last kind have put me to some little 

 inconvenience. 1 shall now detail these effects. 



yi[}f)le-trees. — In every case where the buds were not touched, 

 every beneficial effect has followed the application of oil to the 

 stems and branches. Fruit-buds, if touched, are destroyed ; 

 and also, if far advanced, the leaf-buds. But new buds of both 

 kinds are afterwards produced in great numbers ; and I re- 

 marked on two young trees with lung bare stems, that buds burst 

 forth on the steujs, where none had appeared before. This is 

 easily accounted for. The sap not being able to find the usual 

 outlet in the expansion of the buds formed the previous year, 

 acted 80 as to produce new buds and branches, in the same 



• From the Transactions of the Caledonian Horticultural Society. 



+ The scale has, I understand, been lately discovered to be the nidus, in 

 which the eggs of gome winded insects are depo>ittd. Larv.x have been 

 obse^^'ed to issue from it, but tbey have not yet been found in the pupa 

 Kate. 



F f 3 manner 



