2 BULLETIN 1040, U. S. DEPARTMENT OE AGRICULTURE. 
considered it a new species and gave it the name P. cltrophilus. 
During the first four years various measures of control were tried 
bv the growers and county and State officials without any marked 
success; in fact, the infested area continued to increase rapidly and 
the infestations became more severe. 
The importance of this pest to the citrus industry and inability to 
control it led. in the summer of 1917, to a request for the United 
States Department of Agriculture to take up the problem, and the 
investigation was immediately started. Effective control methods 
were worked out in 1917 and 1918 and were generally employed 
throughout the infested area during 1919. 
SAN BERNARDINO 
Cucamoxga 
• Riverside 
RIVERSIDE 
SAN DIEGO 
Fig. 1. — Present known distribution of the citrophilus mealybug (Pseudococcus gahani) 
in Southern California. 
HISTORY AND DISTRIBUTION. 
Definite records of the introduction of this mealybug into South- 
ern California are lacking, but a study of its earliest occurrence and 
spread would indicate that it was brought in on some ornamental 
plants imported into Upland during 1910. The infestation of about 
3 acres at the time of the first records (1913) had spread by the fall 
of 1915 to twice that area. By 1917 approximately GOO acres were 
infested, but since that time its spread has been greatly retarded by 
control means, though a few small infestations outside of the control 
area have been noted (fig. 1). 
Shortly after the discovery of the Upland infestation the pest was 
found in Pasadena and has now become distributed over a consider- 
