116 



THE MONTHLY BULLETIN. 



THE CITRUS WHITE FLY. 



Dialeurodes citri (Riley and Howard). 



The citrus white fly was undoubtedly imported into California before 

 the quarantine against this insect was declared in 1906, and evidently 

 became established in at least four places before that time. These 

 places are Oroville, Marysville, Sacramento and Bakersfield.* A report 

 which has not been verified also listed Visalia as once having an infested 

 tree, but this was evidently a mistake, as repeated efforts have failed 

 to locate it there. In 1907 the first infestation was discovered at 

 Marysville and a campaign of extermination was begim b}^ the State 

 Commissioner of Horticulture, who succeeded in stamping it out at 

 Oroville, Sacramento and Bakersfield. Other attempts were made in 



Map showing the dis- 

 tribution of the citrus 

 white fly, Dialeurodes 

 citri (R.& H.), in Cal- 

 ifornia, January I916. 

 Circles show where 

 insect formally 

 occurred. 



Essig 



Fig. 44. — Showing the distribution of the 

 citrus write fly, Dialeurodes citri, in California. 

 (Original.) 



recent years to finish the work of extermination at Marysville, but 

 resulted only in the reduction of the infested area and failed to accom- 

 plish the desired end. However, adequate steps have been taken by the 

 State Commissioner of Horticulture to prevent further distribution 

 from this center. 



■■The white fly at Baker.sfield was not the citrus white fly, but another citrus infe-st- 

 ing species, Dialrurodes citrifolH (Morgan), known as Aleyrodcs nubifera Berger in 

 Florida (Inj. & Ben. Tns. CaL, 2d edit., Cal. Hort. Com., p. 195, 1915). 



