THE ARGENTINE ANT IN RELATION TO CITRUS GROVES. 
27 
From May 17 to July 17 the mealybug enemies rapidly decreased 
and disappeared from branches kept free from ants and greatly in- 
creased on those where ants were present, following, as would 
naturally be anticipated, the available food supply. In the succeed- 
ing period of the experiment, from July 17 to September 2, after a 
certain amount of fluctuation, depending upon the supply of host 
insects, the natural enemies finally disappeared from all branches 
with the practical disappearance of their prey. 
Experiment II. 
The second experiment was conducted in the same locality, at 
Alhambra, Cal., on eight bearing navel-orange trees, four of which 
were banded with adhesives on April 24 and kept free from ants, 
while the alternating four were left accessible to ants for compari- 
son. The results of this experiment, which are summarized in Table 
V, were similar to those in the preceding experiment, except that 
on the ant-invaded trees heavy mealybug infestation persisted 
throughout the experiment, or until September 12. 
Table 
V. — Effect of the Argentine ant on abundance of 
trees, Los Angeles County, Cal., 1916 
mealybugs on orange 
Ants present. 
Ants excluded. 
Mealybug infestation. 
Mealybug infestation. 
Date. 
On fruits. 
On other parts of 
trees. 
On fruits. 
Total 
number 
exam- 
ined. 
Num- 
ber in- 
fested. 
Per 
cent in- 
fested. 
Total 
" num- 
ber ex- 
amined. 
Num- 
ber in- 
fested. 
Per 
cent in- 
fested. 
On other parts of 
trees. 
May 24 
July 10 
July 24 
Aug. 7 
Aug. 31 
Sept. 12 
800 
1,405 
1,261 
1,596 
1,310 
1,249 
1200 
328 
766 
923 
728 
421 
25 
24 
60.7 
57.8 
55.5 
33.7 
Approximately as on 
Apr. 24. 
242 groups of 1 to 5 
mealybugs. 
296 small groups, 
many scattered 
young. 
206 small groups, 
many scattered 
young. 
Many scattered 
do 
800 
1,154 
1,263 
1,288 
1,086 
1,282 
U50 
5 
34 
91 
59 
64 
18.7 
.43 
2.6 
7. 
5.4 
4.9 
Approximately as 
on Apr. 24. 
12 groups of 1 to 5 
mealybugs. 
7 small groups, 
many scattered 
young. 
Many scattered in- 
dividuals. 
None. 
Do. 
1 From 1 to 5 mealybugs hidden under the sepals only of each infested fruit. 
At the beginning of this experiment, April 24, mealybug infesta- 
tion was slight, only 103 scattered individual mealybugs and small 
groups occurring on the trees from which ants were excluded and 7(J 
individuals and small groups on those to which ants were allowed 
access, the ant-excluded trees being slightly more infested. 
On May 24 young mealybugs were found concealed under the 
sepals of 25 per cent of the young fruits on the ant-invaded trees 
