CONTROL OF ARGENTINE ANT IN CALIFORNIA. 
23 
of the trees in the orchard. With the approach of the middle of 
August the ants were practically controlled throughout the orchard. 
Progress (fig. 9) is naturally slower from the standpoint of eradi- 
cation than of control. For the first month eradication of ants 
from trees was constant and rapid, 52 per cent of the entire orchard 
being freed within this time. Then eradication slackened and for the 
succeeding 6 weeks made no noticeable gains. By the middle of 
August an increased number of trees were free of ants and this con- 
tinued until by the middle of November ants had been eradicated 
Fig. 9. — Progress of ant eradication on a 10-acre citrus orchard. 
from 92 per cent of the trees, those remaining being mostly marginal 
and attended by a few stragglers from adjacent property. 
It should be noted in presenting the marked success of this experi- 
ment that the trees were quite free of scales, although a few mealy- 
bugs were present. Therefore the food supply was not particularly 
abundant. Likewise worthy of note is the fact that this orchard 
had been severely infested with Pseudococcus citri for four years 
prior to ant control but since then this pest has been effectively 
controlled by its natural enemies. 
