156 Principles of Plant Culture. 



insects and are controllable by the same methods, we do 

 not distinguish between them in the following paragraphs. 



277. Many Insects are Beneficial by destroying harmful 

 insects or by promoting pollination (151). We should 

 nob, therefore, wage indiscriminate warfare upon all 

 insects. 



278. Methods of Preventing Insect Ravages to plants 

 are various, as inclosing the plants, trapping, repelling 

 or removing the insects, destroying them by means of 

 insecticides, or preventing reproduction by destroying the 

 eggs. The important question in the case of any injur- 

 ious insect is by which one of these methods it may 

 be most effectually and cheaply controlled. 



279. Inclosing the Plants is practicable in a few cases, 

 as with the striped cucumber beetle.* The hills in 



which cucumbers, mel- 

 ons, squashes etc., are 

 planted, may be covered 



FIG. 67. Screen-covered frame for pro- with a frame having 

 tecting hills of the melon and cucumber. fine . meshed wire _ or 



cotton netting tacked over the top, which prevents the 

 beetles from gaining access to the plants (Fig. 67). 



280. 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 fre- 

 quently 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 poisoning the 

 herbage (284), some of the cutworms may be killed, 

 but many are likely to escape unless destroyed by other 

 means. 



* Diabrotica vittata. 



