336 On Blight. 



any other, and into which no new trees had been conveyed. 

 But these situations were in the bottom of valleys; and I have 

 observed that it ascends the acclivity of a hill very slowly. 

 Many efforts have been made to deliver our orchards from 

 this new, spreading, and destructive pest; but it seems to 

 me that they have failed of success, chiefly for want of keeping 

 the proper object in view. The destruction of this insect is 

 easy, so far as it can be reached : but in an extensive orchard 

 it is impossible to search every crevice ; and none of the 

 applications that have been recommended even profess to 

 answer the principal requisite, of rendering the tree an un- 

 pleasant situation for the bug in time to come. Yet without 

 this, even if all in the orchard were destroyed, they would 

 soon cross again the hedges from the neighbouring trees. 

 For the destruction of the American blight, or bug (the latter 

 name, at least, is improper, if names are of consequence), it is 

 requisite that the application made use of should extend its 

 efficacy into crevices to which it cannot be, and has not been, 

 injected; its virtues should endure for some considerable 

 period ; it should be not expensive, and not hurtful to the 

 trees. My experience of about two years enables me to 

 speak favourably of the diluted sulphuric acid in this respect 

 (such as is used in apothecaries' shops), which is formed 

 of the mixture (made slowly) of three quarters of an ounce mea- 

 sure of the sulphuric acid with 7|; oz. of water. Care should be 

 taken not to let it touch the garments of the operator, in which 

 it will make holes. It should be applied all over the bark by 

 means of rags, the only parts exempted being the present 

 year's shoots, which it would destroy. It desti'oys moss and 

 lichens, as well as insects ; and if applied in showery weather, 

 will be washed into every crevice in which they can harbour. 

 The insects which are touched with it immediately die ; and 

 those that have not been touched with it very soon cease to 

 yield so large a secretion of cotton ; by which means, if it be 

 true that the young ones are conveyed by the winds wrapped 

 up in this mantle, their propagation must be much curtailed. 

 After the application of the acid, when the weather has been 

 fair, I have seen them in crevices, still busily at work ; but, 

 on the occurrence of a rainy day, which, I suppose, has in- 

 undated them with the poisonous fluid, they have been found 

 all dead. I have seen a small tree, that before seemed to 

 languish, thrive remarkably in the second season following 

 the application of the acid ; a proof that, at least, it is not 

 injurious to vegetation. This fluid has the recommendation 

 of being void of the offensive odour of some that have been 

 used for the purpose ; and, so far from being unsightly, as 



