INSECTICIDES, PREVENTIVES, AND MACHINERY. 431 



as might emerge would find themselves in a prison from which 

 there is no escape, and would die shortly, if, indeed, they be not 

 killed through the netting. 



Wrapping with newspapers or similar material is also a tolera- 

 bly effective measure, and such a wrapper will last a season with- 

 out attention, except a possible retying. Tarred paper has been 

 recommended, and is more lasting ; but it seems to cause injury 

 on thin-barked trees, especially peach and young apple, in some 

 sections of the country. The tar really adds nothing to the 

 effect, and, as there is an element of danger, the use of such paper 

 is not recommended. Such wrappings are mostly used to keep 

 out borers that enter near the base : they should cover com- 

 pletely, should extend at least eighteen inches from the surface, 

 should be well tied at the top with a soft twine that will yield to 

 some growth without breaking, and should extend an inch or 

 two below the surface. Besides keeping out borers from points 

 so protected, the coverings would tend to keep in such insects as 

 might develop, and would prevent their emergence and propa- 

 gation. 



Instead of wire or paper coverings, a coating of tree-lime, 

 Raupenleim, bird-lime, printer's ink, or other sticky substance 

 is sometimes employed. Some of the materials once suggested, 

 like dendrolene, turned out to be vmsatisfactory, because the 

 vaseline they contained gradually worked through the bark, into 

 the sap-wood, and caused serious injury. A complete covering 

 with any such material is no longer recommended ; but as a 

 banding to prevent the ascent up the trunk into the tree some of 

 them serve an excellent purpose. 



Several such tree coverings are on the market at present, and 

 almost any of them applied in a ring from four to six inches wide 

 will serve to keep crawling insects from getting into the tops. 

 They are especially useful as against canker-worms and the like 

 by keeping off the wingless females and, later, the caterpillars. 



Gas-tar, coal-tar, and similar materials are sometimes advised 

 for use at the base of peach-trees, and all of them have a record 

 for effectiveness and safety in the hands of careful experimenters ; 

 unfortunately, these same substances have proved dangerous in 

 other hands and in other localities. Climatic conditions seem to 

 be of importance in some inexplicable way, and nothing that has 

 been ever known to cause injury should be extensively used by 



