THE COMMON MEALYBUG IN CALIFORNIA. 5 



CONTROL OF THE MEALYBUG. 



Three methods of control — fumigation, spraying, and the coloni- 

 zation of natural enemies— have played an important part in com- 

 bating the mealybug on citrus trees and have been esteemed variously 

 as the most promising. The studies carried on in southern Cali- 

 fornia by this department indicate that no one of these control 

 methods is applicable or preferable under all conditions of infesta- 

 tion, but by proper combination of these methods, and with the addi- 

 tion of banding to exclude ants, satisfactory control may be accom- 

 plished. 



FUMIGATION. 



Fumigation with hydrocyanic-acid gas as generally practiced for 

 the black and red scales is a failure against mealybugs. No instance 

 has been observed where the usual commercial treatment of an in- 

 fested orchard with this gas has controlled this pest. Although 

 records taken within a few weeks after fumigation have shown a 

 reduction of the mealybug, such reduction was found invariably to 

 be due largely to the action of natural agencies and doubtless would 

 have occurred even though the trees had not been treated — a consider- 

 ation seldom taken into account by the orchardist or commercial 

 operator. 



2. — A group of common 



•a about 9 times. 



