24 



BULLETIN 965, TJ. S. DEPARTMENT OF AGEICULTUKE. 



Table 1. — Effectiveness of Barber poisoned sirup in the control of the Argentine 



ant in a citrus orchard. 





Dates of inspections. 





>> 



■ 3 



1-3 



1-3 



>-3 



l-s 



to 



CO 



< 





•o 



P. 

 m 



15 

 -O 





Free of ants 



P.ct 

 15 

 26 

 59 



74 



P.ct. 

 28 

 11 

 61 



89 



P.ct. 

 52 

 11 

 37 



89 



P.ct. 



44 



4 



52 



96 



p.ct. 



55 



2 



43 



98 



p.ct. 



54 



1 



45 



99 



P.ct. 

 63 



36 



99 



P.ct. 

 72 



i 



27 



99, 



P.ct. 

 81 

 

 19 



100 



P.ct. 

 69 



30 



99 



P.rf. 

 92 



Trails of ants 







Few straggling ants. . . 



8 



Either free of ants or with few 

 stragglers only 



100 







Orchard B, located at Upland, Calif., consisted of 6 acres of Valen- 

 cias and 4 acres of naval oranges, with a total of 674 trees. They 

 were very large, being about 25 years old, and quite severely infested 

 with the citrophilus mealybug. The lower limbs which rested on 

 the ground were trimmed up, thereby forcing the ants to ascend the 

 trunks. The orchard was in a clean state of cultivation with no 

 vegetation growing beneath the trees. The ant sirup was prepared 

 according to the original Barber formula and put out in 1-pound 

 paraffined paper bags, one to each tree as described in orchard A. 

 The distribution of the sirup was completed October 5, 1917. A 

 careful inspection was made from time to time to note the stability 

 of the sirup and its effectiveness against the ants. Some crystalli- 

 zation appeared within 6 weeks, and by the end of the second month 

 practically all had hardened. The ants fed heavily on the sirup 

 before crystallization took place and their numbers became greatly 

 reduced during the autumn months. Although prior to the sirup 

 distribution only 5 of the 674 trees were free of ants, all theremainder 

 being attended by trails of ants, many having two or even three 

 trails along the trunk, these trails became weaker and weaker and 

 were almost broken by the time the sirup began to crystallize. 



There was slight ant activity throughout the winter, due to the 

 open season. On March 3 and 4, 1918, an inspection of the orchard 

 showed above 99 per cent of the trees entirely free of ants, only 3 

 of the 674 trees being infested. By April 9 ants had invaded the 

 orchard from severely infested adjoining territory, so that 26 trees 

 were infested. Fresh sirup was distributed on these trees at this 

 time, and on June 17 on other marginal infested trees. By June 29 

 ants had been eradicated from 672 of the 674 trees in the orchard, 

 and the experiment stood as a determination of the efficiency of the 

 poisoned-sirup method in orchard eradication jof ants. 



Cost. — The cost of ant eradication in these 10 acres, including the 

 materials, labor in preparation, and distribution of 674 containers in 

 October, 26 in April, and 32 in June (a total of 732), amounted to 

 .03, or 2.6 cents per tree. 



