Canker - I Forms. 2 1 1 



The oldest method is tarring the trees. The tar must be mixed with oil 

 to prevent it from drying too soon, and appUed every afternoon, as the in- 

 sects ascend mostly in the night ; but, if they are very abundant, it may 

 be needful to be done twice in the day. Sometimes such numbers will at- 

 tempt to pass up, that those caught in the tar form a bridge for others to 

 pass over. A drizzly rain during a warm night will soon glaze over the sur- 

 face of the tar, no matter how fresh it may be, so that it is easily passed 

 over ; and such nights are the time when they travel most. Cheap prinling- 

 ink, made for the purpose, has been found to dry less quickly than tar- but 

 care should be taken to procure a proper qualit}', as some has been sold which 

 was entirely unfit for the purpose. The ink, like the tar, hardens by cold. 

 I have seen it so stiff on the north side of a tree, that it was no hinderance 

 to the ascent of the insects; and, at the same time, it was so soft on the south 

 side as to run down : when this is the case, stirring up the surface with a 

 brush will be just as effectual as applying more ink. Neither tar nor ink 

 should be applied directly to the tree, but on a strip of cloth or coarse paper 

 fastened round it. A stout string around the lower edge will prevent the 

 tar or ink from running down on the bark below. 



A better but more costly method of applying tar or oil, or a mixture of 

 both, is to make a trough round the tree, and fill it. It must be watched and 

 renewed from time to time, and the leaves which blow in removed, so that 

 the insects may not pass over on them ; and wind will blow out the oil, 

 but there is far less danger of its being filled with the dead insects. The 

 best way of making the trough is to place it on a box around the tree, fill- 

 ing in the box with tan. The trough may be made of roofing-tin, or of a 

 gutter grooved out of wood, and nailed round the box, and, in either case, 

 should be sheltered by a roof A very neat patent tin trough is made by 

 Mr. Hilton of Providence, R.I. ; which is, however, too expensive for use, 

 except for a very few trees, or where neatness is an object. When carefully 

 attended, the trough of oil is substantially effectual ; but, without watching 

 carefully, no remedy will be of much use. A patented protector made of 

 strips of mica I have found entirely useless ; and another protector, con- 

 sisting of a circle of glass in sections, I should not think would be much 

 better, though I have never tried it. Ordway's protector, which is a collar 

 of sheet-zinc placed at such an angle as to be difficult for the grubs to pass 



