Mechanical Destruction of Insects 145 



the batting can be turned over and down like an inverted 

 tunnel, which forms the .bar to the ascending caterpillars. 

 The caterpillars collect below the band and should, from 

 time to time, be gathered and killed. A band of tarred 

 paper may be substituted for the cotton, or else light burlap 

 (eight ounce, eight to ten inches wide). These devices 

 are not very sightly; a neat metal protector, consisting of a 

 brass band with teeth like a comb, tacked to the tree, is an 

 improvement upon them, as regards appearance. Where 

 the bark is rough, it may become necessary to smooth it, 

 so that the band makes a tight joint. Where a large num- 

 ber of trees are to be protected, as in streets and parks, it 

 will be found cheaper to use a band made of a sticky sub- 

 stance. For this purpose there are several preparations 

 made from crude petroleum; a German one sold under the 

 name "Raupenleim" * was the original one, an American 

 one called "Dendrolene," ^ and another, "Tree-Tanglefoot," 

 all more or less greasy, smooth, and of butter-Hke consist- 

 ency. The last mentioned remains effective a longer time, 

 because it does not dry, but it is apt to injure the bark of 

 young trees, hence in such cases it should be applied with a 

 protective paper band underneath. 



These applications are made, after having smoothed the 

 bark, three tfi six inches wide and a quarter of an inch thick. 

 There are devices for handling these substances expeditiously, 

 but ordinarily a trowel may be used. The bands should be 

 placed at sufficient height to avoid disagreeable accidents 

 from contact with passers-by. Should the band become dry, 

 it will have to be renewed. 



These coatings can also be used to advantage to keep 



' To be obtained from Bowker Fertilizer Co., Boston; Wm. Mengel 

 Son, New York. 



' To be obtained from Prof. F. L. Nason, New Brunswick, N. J. 



