24 
BULLETIN 965, U. S. DEPARTMENT OF AGRICULTURE. 
Table 1. — Effectiveness of Barber poisoned sirup in the control of the Argentine 
ant in a citrus orchard. 
Dates of inspections. 
03 
<B 
d 
CO 
3 
OS 
>> 
.5 
3 
P, 
as 
O 
> 
o 
Free of ants 
P.ct 
15 
26 
P.ct. 
28 
11 
P.ct. 
52 
11 
37 
89 
P.ct. 
44 
4 
52 
96 
P.ct. 
55 
2 
43 
98 
54 
1 
45 
99 
P.rt. 
63 
P.ct. 
72 
P.ciL 
81 

19 
100 
P.pf. 
69 
t 
30 
99 
P.ci. 
92 
Trails of ants 
i i 
4 4 
36 27 
99 99 

59 j 61 
71 89 
8 
Either free of ants or with few 
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 the remainder 
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 of 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 
$19.03, or 2.6 cents per tree. 
