PLANTS AND ANIMAL PARASITES 155 



and the like are planted, may be covered with a frame 

 having fine-meshed wire or cotton netting tacked over 

 the top, which prevents the beetles from gaining access 

 to the plants (Fig. 67). 



279. Trapping the insects is practicable in a few 

 cases, as with cutworms, which often conceal themselves 

 during the day beneath objects on the ground. They 

 will frequently be found in numbers beneath handfuls 

 of green clover or other herbage placed on the ground 

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

 soning 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 (Melittia satyriniformis) . 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 (Phlegethontius sexto) and other large insect larvae 

 and the rose-beetle (Macrodactylus subspinosus) . A 

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

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

 venient 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 bettle (Leptinotarsa decemlineata) . 

 Digging out cutworms and white grubs (Lachnosterna) 

 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. 



