THE ARGENTINE ANT IN RELATION TO CITRUS GROVES, 33 
In San Diego County, therefore, the conditions are such that the 
mealybug infestation is just as persistent in trees where there are no 
ants as in other localities overrun by them. This infestation may 
remain severe for from one to several seasons, and then there will 
come a period when the mealybugs will disappear almost wholly. 
This fact has just been illustrated in the Chula Vista district, and 
is no doubt due to variations in abundance of the mealybug enemies 
in that section. 
INFLUENCE OF THE ANT ON ABUNDANCE OF OTHEE MEALYBUGS IN CALIFORNIA. 
The number and severity of outbreaks of other species of mealy- 
bugs in Pasadena have been increasing during the last three years. 
Dr. A. G. Smith, county horticultural inspector for the Pasadena 
District, states that in an inspection five years ago, covering the dis- 
trict bounded by Fairoaks, Colorado, and Lake Streets and the Alta- 
dena boundary line, only one mealybug infestation was found. An 
inspection three years ago of the same section of Pasadena produced 
18 infestations, mostly on rice-paper plants. During the summer of 
1916, up to the time this information was given, only the north half 
of this section, or from the Altadena line to North Orange Grove 
Avenue, had been inspected, but infestations were found in numerous 
places and on many more host plants than ever before. The worst 
of these outbreaks have occurred in territory invaded by the Argen- 
tine ant, and undoubtedly have been especially severe and persistent 
only where attended by this ant. 
A number of the outbreaks discovered by Dr. Smith's inspectors 
early in the summer of 1916 had been greatly reduced, and the mealy- 
bugs had almost disappeared by August where there were no ants in 
attendance. The species concerned in these outbreaks and the host 
plants most commonly infested in this section are as follows : Pseudo- 
coccus citrophilus Glaus, on pittosporum, oignonia, tecoma, citrus; 
Pseudococcus hakeri Essig. on Chamaerops and Washington palms, 
peppers, laurestinas, nightshade, tomato, banana, aralia, fig, cam- 
phor, and various garden plants; Pseudococcus longispinus Targ. 
on Dracaena palms, citrus, and some shrubs ; Pseudococcus ryani Goq. 
on cypress hedge. Outbreaks of these species of variable degree 
occur every spring, but are less persistent and usually are controlled 
early by their natural enemies where no ants are present. 
Another species, known as the golden mealybug (Pseudococcus 
t aurilanatus Mask.), attacks the Araucaria tree in many localities 
about Pasadena and remains numerous throughout the summer, 
regardless of whether ants are present or not, and often causes the 
defoliation of the trees. This mealybug either is not controlled by 
