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 coHtrol. 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. — l'ro;;ress of ant criKiiialioii on a lO-acni cilriis orchard. 



from 92 per cent of the trees, those remaining being mostly marginal 

 and attended by a few stragglers from adjacent property. 



It shoukl 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 Psfudococcus citri for four years 

 prior to ant control but since then tliis pest has been effectively 

 controlled by its natural enemies. 



