20 BULLETIN 965, U. S. DEPARTMENT OF AGRICULTURE. 
An inspection February 7, 1918, showed that some ants had colonized 
in the cans, hut in the absence of heavy rains the ants were continuing 
largely in their ground colonies. A final inspection March 18, 1918, 
showed that only 41 per cent of the cans contained nests, and these were 
for the most part small. Many colonies were found in the ground 
beneath the cans or even at the base of the trees near the cans; in fact, 
in all cases the preponderance of ants in the orchard sfppeared to be 
outside the cans. The cans were fumigated with carbon disulphid 
immediately following the final inspection. An inspection of the 
entire grove in May showed the ants as prevalent in the part over 
which ant traps were distributed as in the check plot, thus demon- 
strating the futility of ant control in California by the trap-nest 
method recommended for Louisiana. 
A second experiment in an adjacent -grove with 50 trap boxes 
during the same winter gave no better results. 
The success of trap nesting, as pointed out by Newell and Barber, 
depends upon rainy weather. The winter of 1917-18 was a warm 
and open one with light rains, and this resulted in ants being more 
or less active in southern California throughout the season. It is 
very probable that in a colder winter with heavy rains trap nests 
would be more successful. Even under the most ideal conditions 
for trap nesting, however, this method would be less effective and 
more costly than the poisoned-sirup method later taken up in this 
publication. 
POISONED SIRUPS. 
Eradication is the ideal to be sought with any pest and particu- 
larly does this apply to the Argentine ant. Once the ant is eliminated 
from a grove, future effort can be restricted to protecting the borders 
from invasion from neighboring property. The most effective 
method of eradication tried in California has been the use of a 
poisoned sirup, which is eaten by the ants. For the most part 
arsenic in some form constitutes the toxic substance of such a poison, 
although a few nonarsenicals have been used. 
In all orchard work small containers of tin or paraffined paper 
were used, partly filled with sirup and hung one to a tree, the ants 
entering through small holes in the sides. 
Chloral Hydrate. 
Chloral hydrate was recommended by Horton 9 as the best poison 
for orchard use. It is prepared as follows: 
Make a sirup by stirring 8 pounds of granulated sugar in one-half gallon of cold 
water until dissolved, making 1J gallons of sirup. Then add 4§ ounces of chloral- 
s' Horton, J. R, control of the argentine ant in orange groves. U. S. Dept. Agr., Farmers' 
Bui. 928, p. 19. 1918. 
