THE ARGENTINE ANT IN RELATION TO CITRUS GROVES. 69 



After the eighth fumigation, February 27, 1915, there was very 

 decided reduction in the number of ants in the orchard, and the fore- 

 man of the place remarked that the ants were getting very scarce in 

 the block. Only straggling workers occurred in a few of the traps 

 from this time until the next fumigation, June 7. On March 25 

 examination of 30 orange trees revealed only one scout ant, and it 

 was reported that there were no more ants about. A ranch hand said 

 he had uncovered only three nests in plowing the entire block, while 

 in a neighboring orchard (which had been treated for ants by the 

 flooding method for three years or longer) he had raised so many 

 he could not keep track of them. On the same date the ants were 

 extremely numerous in the orange trees in an adjoining grove. 



A further examination on April 16 showed ants to be present on 

 only 1 in 40 trees, and then not numerous enough to form trails. 

 There were no ants at the blossoms or at the numerous aphids on the 

 trees. Some large umbrella trees, which usually had from six to eight 

 large trails, were absolutely free from ants. In the house it was no 

 longer necessary to isolate food supplies, beds, etc., from the ants, 

 from which there was not the slightest further annoyance, as stated 

 by both the foreman and his wife. In the upper portion of the same 

 property, about 90 rows from the experimental block, on the con- 

 trary, the ants were running in heavy trails up all the trees and were 

 numerous in the blossoms and at aphids. 



After the February fumigation another was not warranted for 

 about three and one-half months, or until June 7, when 21 of the 

 traps contained sufficiently large colonies to seem to warrant their 

 destruction. The killing of queens had been reduced from nearly 

 300,000 in each of the first three or four fumigations to less than 

 5,000, and, of course, all the other stages had been comparably 

 reduced. The experiment was a complete success, for it reduced the 

 ants to negligible numbers. 



The following rough but not widely erroneous estimates will give 

 an idea of the populousness of the ants in this orchard: The total 

 estimated number of queens killed, as reference to Table VII will 

 show, was 1,307,222. The workers and young must be estimated by 

 volume. In the first four fumigations every trap fumigated con- 

 tained fully one-half gallon of ants in all stages, and in each of the 

 succeeding five nearly a quart. The total number of traps fumigated 

 in the first four operations was 1,568; therefore 784 gallons, or about 

 15-J barrels, of ants were destroyed. In the remaining five fumiga- 

 tions there were 1,543 traps; therefore about 385 gallons, or about 

 7| barrels, of ants were destroyed. The bulk of the ants destroyed 

 in this work, therefore, would be almost great enough to fill twenty- 

 three 50-gallcn barrels. 



