INSECTS IN THE SOIL. 53 



For practical purposes, the numerous insects infesting fruit 

 trees may be divided into four classes ; 1st, those which for a 

 time harbour in the ground and may be attacked in the soil; 2d, 

 winged and other species, which may be attacked among the 

 branches ; 3d, aphides, or plant lice which infest the young 

 shoots ; 4th, moths, and all night-flying insects. 



Insects, the larva, or grubs of which harbour in the ground during 

 a certain season, as the curculio or plum- weevil, are all more 

 or less affected by the application of common salt as a top dress- 

 ing. On a larger scale in farm crops the ravages of the 

 cut- worm are frequently prevented by sowing three bushels of 

 salt to the acre, and we have seen it applied to all kinds of fruit 

 grounds with equal success. Salt seems to be strongly disagree- 

 able to nearly all this class of insects, and the grubs perish, 

 where even a small quantity has for two or three seasons been 

 applied to the soil. In a neighbourhood where the peach worm 

 usually destroys half the peach trees, and where whole crops of 

 the plum are equally a victim to the plum- weevil, we have seen 

 the former preserved in the healthiest condition by an annual 

 application of a small handful of coarse salt about the collar of 

 the tree at the surface of the ground ; and the latter, made to 

 hold abundant crops, by a top dressing applied every spring of 

 packing salt, at the rate of a quart to the surface occupied by 

 the roots of every full grown tree. 



Salt, being a powerful agent, must be applied for this purpose 

 with caution and judgment. In small quantities it promotes 

 the verdure and luxuriance of fruit trees, while if applied 

 very frequently, or too plentifully, it will certainly cause the 

 death of any tree. Two or three years top-dressing in moderate 

 quantity will usually be found sufficient to drive away these in- 

 sects, and then the application need only be repeated once in two 

 or three seasons. Any coarse, refuse salt will answer the pur- 

 pose ; and packing salt is preferable to that of finer quality, as it 

 dissolves slowly by the action of the atmosphere. 



In the winged state, most small insects may either be driven 

 away by powerful odours, or killed by strong decoctions of to. 

 bacco, or a wash of diluted whale-oil or other strong soap. At- 

 tention has but recently been called to the repugnance of all in- 

 sects, to strong odours, and there is but little doubt that before 

 a long time, it will lead to the discovery of the means of pre- 

 venting the attacks of most insects by means of strong smell- 

 ing liquids or odourous substances. The moths that attack furs, 

 as every one knows, are driven away by pepper-corns or tobacco, 

 and should future experiments prove that at certain seasons, 

 when our trees are most likely to be attacked by insects, we may 

 expel them by hanging bottles or rags filled with strong smelling 

 liquids in our trees, it will certainly be a very simple and easy 

 way of ridding ourselves of them. The brown scale, a trouble- 



