194 DISEASES AND INSECT ENEMIES. 



fumes of this gas are stupified for a time, but they 

 soon recover and in a few hours are as active 

 as ever. 



Soaps of all kinds are effective in destroying 

 both old and young mites, and also kill a large 

 proportion of the eggs. On account of the diffi- 

 culties in using soap, however, it cannot be 

 generally recommended, but for certain pur- 

 poses, which will be referred to later, it will 

 be found very useful. 



Water applied to the foliage is the only 

 effective remedy that can be depended upon for 

 this pest.-^ It must be applied, however, with con- 

 siderable force, the object being to wash both 

 mites and eggs from the leaves. To do this 

 successfully and at the same time not injure the 

 plants and not bring about conditions favorable for 

 other diseases, such as spot, is a difficult problem. 

 The chief point in this work is to keep the spiders 

 so thoroughly in check that by the time the plants 

 have attained nearly their full growth in the fall, 

 that is, by the middle of September, spraying can 

 be entirely stopped, and from that time on during 

 the winter little or no water need be applied to 

 the foliage. We have found that where spiders 

 are washed from the leaves a certain per cent of 

 them get back. Many are killed by the direct 

 crushing action of the water, and thousands not 

 destroyed in this way are knocked off into the soil 

 and probably starve to death before they can 



