CONTROL OF ARGENTINE ANT IN CALIFORNIA. 
19 
success attending this method in the Southeast induced the writers 
to conduct an experiment under the more arid conditions in the South- 
west. 
A 10-acre orange grove at Upland, Calif., very severely infested 
with Argentine ants, was selected for the experiment. Five-gallon 
tin coal-oil cans (9J by 9| by 13^ inches) were used for traps (see 
fig. 8), being much cheaper than the. wooden boxes, and affording 
complete protection from rain or winds. One end was cut along three 
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Fig. 8. — Winter trap nest, consisting of 5-gallon oil cans filled with 
nesting material, in place at base of tree. 
sides and this acted as a flap over the entrance of the can, protecting 
it from beating rains. Three hundred and fifty cans were used, being 
divided into seven lots of 50, each lot containing a different filler. 
These were respectively green grass and dirt, green grass, green alfalfa, 
dry straw, wet straw, moist dirt, dirt, and leaf mulch. The cans were 
placed on a side, close up to the base of the tree. Approximately 3 of 
the 10 acres were reserved as a check, the remaining 7 being covered 
with ant traps, one to each tree on about 3 acres and one to every 
other tree on the remainder. These were placed December 1, 1917. 
