Plants as Affected by Animal Parasites. 163 



of green clover or other herbage placed on the ground 

 near the plants which it is desired to protect. By pois- 

 oning the herbage (283), some of the cutworms may be 

 killed, but many are likely to escape unless destroyed by 

 other means. 



280. Repelling Insects by means of offensive odors is 

 partially effective in some cases, as with the squash- 

 vine borer.* Corncobs or other objects, dipped in coal 

 tar and placed among the plants, repel many of the 

 moths that produce the borers. 



281. Hand Picking, i. e., removing the insects from 

 the plants by hand, is the most satisfactory method for 

 destroying certain insects, as the tobacco or tomato 

 worm,t and other large caterpillars, and the rose-beetle.J 

 A vessel of water with a little kerosene on the surface, 

 in which to throw the insects as they are gathered, is a 

 convenient way of destroying them. In some cases, the 

 insects can be shaken or knocked from the plant directly 

 into the vessel. This method is often employed in de- 

 stroying the potato beetle. § Digging out cutworms and 

 white grubs** from about corn and strawberry plants, 

 and cutting out borers from trees and squash vines are 

 often the most effectual methods for destroying these 

 insects. 



282. Destroying Insects by Poisons or Caustics is 

 the method most generally available. The material 

 used is called an insecticide (in-sect'-i-cide), and if sat- 

 isfactory, must be destructive to the insects without in- 

 juring the plant to which it is applied, or rendering 



* MeUtia eeto. t Phlegethontius celeus. t Macrodactylus sutspinosua. 

 § Doryphora decemlineata. ' * Lachnosterna, 



