No. 7. DEPARTMENT OF AGRICULTURE, 299 



beneficial in driving away the enemies of the latter. Another plant 

 likewise recommended for the same purpose is buckwheat, a few 

 grains of which scattered among cucumber hills have been said to 

 prevent the occurrence of the striped cucumber bugs. (An auditor 

 here said that he had prevented the occurrence of these bugs in his 

 cucumber fields by scattering walnut leaves among the plants.) 



II. The second great group of preventives is to be called me- 

 chanical. By this we mean any obstruction that will prevent the 

 insect from getting to the plants. The efficiency of mechanical 

 devices depends upon the completeness with which plants are pro- 

 tected, especially while they are young. It is well known that at- 

 tacks upon young plants are much more serious than upon older 

 ones. Among the mechanical appliances that have been used with 

 satisfactory results, one should mention wire netting put around 

 fruit trees for borers. This should not touch the tree, as there is 

 danger of eggs being laid through the meshes of the wire where it 

 lies directly in contact with the bark. Paper closely wrapped 

 around the tree serves the same purpose, and sticky substances, 

 such as raupenleim and dendrolene, are also highly recommended 

 as a means of protecting the trees from borers. A similar means 

 of protection is a coating of paint made of pure white lead and 

 linseed oil, of the consistency of cream or regular house paint, 

 and applied to the trunks of the trees, down as far as possible, with 

 a paint brush. Professor Alwood, of Virginia, has painted thou- 

 sands of trees in this way, and reports that all haA^e been protected 

 in a proper manner and none have been injured. 



Among the mechanical devices, we should mention barriers to pre- 

 vent climbing cutworms, canker-worms and other insects from as- 

 cending the trees. Bands of loose cotton tied around the trees will 

 be found effective for this. Also, sheets of paper, upon which tar 

 has been spread, fastened firmly around the trees as sticky bands; 

 also, metal troughs filled with oil, even sheets of bright, smooth 

 tin fastened around the trees will prove too slippery to prevent the 

 crawling insects passing over them. Various devices have been 

 patented recently and put upon the market for this purpose, but 

 they are to be recommended for only a few insects, such as canker- 

 worms and climbing cutworms. 



If these are to be effective preventives, the time of year they 

 are applied is to be considered. For canker-worms, trees should 

 be banded at this time of year, or about the time the leaves com- 

 mence to fall, since the females are wingless and climb the trees 

 to deposit their eggs. They do this very late in the fall, or very 

 early in the spring. There are two kinds of canker-worms, one 

 called the fall canker-worm, because it climbs the trees and lays 

 eggs in the fall; and the other the spring canker-worm, because it 



