386 PEAR GROWING IN CALIFORNIA. 



drying up or suffocation. Road dust and air-slaked lime are both very 

 effective, their practical use decreasing in proportion to the size of the 

 trees. The application of any insecticide is greatly facilitated because 

 of the habit of feeding on the upper sides of the leaves, making it 

 absolutely unnecessary to pay any attention to spraying from under- 

 neath. While easily controlled, this pest should not be neglected, as 

 frequent defoliation may result in the death of a tree. 



FIG. 178. Larvae and characteristic 

 injury of pear slug, Caliroa cerasi. 



ANTS. 



Various species of this troublesome pest are found in pear orchards, 

 and there is every reason to believe that they are one of the most 

 important factors in the spread of pear blight. In crawling up the 

 trunks and over the branches blight bacteria are carried from live 

 cankers and deposited in blossoms and various other places where they 

 can gain entrance and produce the disease. Once the germs are placed 

 in the blossoms by insects visiting the holdover cankers there is nothing 

 to prevent wholesale spread by bees and other blossom feeding insects. 



Control. 



Tree tanglefoot has already been mentioned as a substance that will 

 prevent ants and other insects from crawling up the trunks. The 

 following formula of the II. S. Bureau of Entomology has been used 

 very successfully in the control of the Argentine ant, and no doubt will 

 prove equally as effective in the case of other species. 



Prepare a sirup : 



Granulated sugar 12 pounds 



Water 7 pints 



Tartaric acid (crystallized) i ounce 



Boil for 30 minutes. Allow to cool. 



Dissolved sodium arsenite (C. P.) f ounce 



In hot water ; 1 pint 



Cool. Add poison solution to sirup and stir well. 



Add to the poisoned sirup: 



Honey , 2 pounds 



Mix thoroughly. 



169 



