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Effective Farming 



be exterminated, it can be controlled to such an extent that 

 the finest fruit can be produced on trees where the pest has 

 existed for years. To control the pest the trees and shrubs 

 should be sprayed with lime sulfur solution. 



The living scale is a very small, soft insect concealed beneath 

 a flat, conical, water-proof protective scale. The scale can be 

 recognized under a miscroscope by its circular shape, black tip 



FIG. 109. Fumigating citrus trees in California with hydrocyanic acid gas 

 to kill scale insects. 



at the center with a very small ring around it. Fig. 110 

 shows the characteristic appearance of the scale on twigs. 

 In the winter this scale is about three-fourths the size of a pin- 

 head and is black in color. This is known as the winter-rest- 

 ing stage. By spring it has increased to about the size of a 

 pin-head and becomes brownish in color. Like other insects 

 of this kind, it attacks its host by inserting its proboscis through 



