336 INSECTS INJURIOUS TO VEGETATION. . 



which they spread year after year. Accident, however, will of- 

 ten carry them far from their native haunts, and in this way, prob- 

 ably, they have extended to places remote from each other. 

 Where they have become established, and have been neglected, 

 their ravages are often very great. In the early part of the season 

 the canker-worms dj not attract much attention ; but it is in 

 June, when they become extremely voracious, that the mischief 

 they have done is rendered ap arent, when we have before us 

 the melancholy sight of the foliage of our fruit-trees and of our 

 noble elms reduced to withered and lifeless shreds, and whole 

 orchards looking as if they had been suddenly scorched with fire. 

 In order to protect our trees fi om the ravages of canker-worms, 

 where these looping spoilers abound, it should be our aim, if pos- 

 sible, to prevent the wingless females from ascending the trees to 

 deposit their eggs. This can be done by the application of tar 

 around the body of' the tree, either directly on the bark, as has 

 been the most common practice, or, what is better, over a 1 road 

 belt of clay-mortar, or on strips of old canvass or of strong pa- 

 per, from six to twelve inches wide, fastened around the trunk 

 with strings. The tar must be applied as early as the first of 

 November, and perhaps in October, and it should be renewed 

 daily as long as the insects continue rising ; after which the bands 

 may be removed, and the tar should be entirely scraped from the 

 bark. When all this has been properly and seasonably done, it 

 has proved effectual. The time, labor, and expense attending 

 the use of tar, and the injury that it does to the trees when al- 

 lowed to run and remain on the bark, have caused many persons 

 to neglect this method, and some to try various modifications of 

 it, and other expedients. Among the modifications may be men- 

 tioned a horizontal and close-fitting collar of boards, fastened 

 around the trunk, and smeared beneath with tar ; or four boards, 

 nailed together, like a box without top or bottom, around the 

 base of the tree, to receive the tar on the outside. These can 

 be used to protect a few choice trees in a garden, or around a 

 house or a public square, but will be found too expensive to be 

 applied to any great extent. Collars of tin-plate, fastened around 

 the trees, and sloping downwards like an inverted tunnel, have 

 been proposed, upon the supposition that the moths would not be 



