398 CITRUS FRUITS AND THEIR CULTURE. 



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common enemies are the scale insects and mealy-bug (Dac- 

 tylopius citri) . The scales can best be held in check, either 

 by spraying, for which purpose Good's Potash Whale Oil 

 Soap No. 3 is recommended, or by fumigating. The 

 mealy-bugs are more difficult to deal with. The cottony 

 substance by which they are generally covered is imper- 

 vious to sprays and the only method which is at all effi- 

 cacious is to go carefully over the trees and brush the 

 mealy-bugs off, then spray thoroughly with whale-oil soap 

 and follow with thorough applications of the same mixture 

 at intervals of ten days. It should be worked-in well so as 

 to penetrate the woolly covering. For further notes on 

 these insects see section on insects. 



