10 BULLETIN 377, U. S. DEPARTMENT OF AGRICULTURE, 
over practically the whole town, as well as near-by corn and cotton 
fields. 
During the same winter (1911-12) similar conditions were expe- 
rienced at New Orleans, the winter months being accompanied by a 
rainfall of 41.56 inches, as compared to the 10-year average of but 
26.1 inches. The numbers of ants were greatly reduced, the mortality 
probably being at least 70 per cent. The ability of this species to 
overcome such a catastrophe was well illustrated, for by September, 
1912, the ants had apparently reached their maximum numbers. 
REPRESSION. 
OUTDOOR BARRIERS. 
A number of experiments have been conducted to discover, if 
possible, an efficient outdoor barrier. 
The sticky substance which is used in coating flypaper and is also 
sold in bulk for banding trees was effective for only a few days. The 
ants would carry particles of dirt and build a bridge over it. This 
substance, made much thinner than usual, as suggested by Mr. D. M. 
Rogers for use in the gipsy-moth work, was tried and with more 
successful results. Heavy bands 4 inches wide spread on two mag- 
nolia trees were effective for two months in the summer without 
having to be replenished or combed. 
In the cooler parts of the year these bands require frequent atten- 
tion on account of the growth of mold on the surface. During wet 
weather in the winter in Louisiana this mold will form in a very 
few days, and the efficiency of the sticky band will be entirely 
destroyed. 
It was found that 5 per cent of a carbolized oil added to the thinner 
preparation increased the effectiveness of the bands considerably 
and entirely prevented the growth of mold. The bands were also 
rendered more repellent and more resistant to winter conditions. <A 
thin crust forms over the surface of the bands in the winter, but this 
is readily combed into the band in the spring and the band is as 
effective as ever. The crust on bands of the thinner preparation | 
‘without the carbolized oil becomes too hard during the winter, and 
it 1s necessary to use fresh material in the spring. These bands 
were used on fig, magnolia, pecan, and orange trees and no injury to 
the trees was apparent. There is a possibility that the substance 
may be harmful to trees with a more tender bark, however. 
To the thinner preparation were added in different tests 1 per 
cent of bichlorid of mercury, 2 per cent of nicotine sulphate, 10 per 
1 A wooden comb is supplied by the manufacturers for the purpose of combing the bands 
when a coating of dirt, insects, or any other foreign matter collects on the band. This 
foreign material is mixed in with a clean sticky substance, immediately under the surface 
of the band, and the band is as efficient as ever. 
