30 
BULLETIN 965, U. S. DEPARTMENT OF AGRICULTURE. 
Sixteen-ounce round baking-powder tins recommended by Barber 
were tried in one orchard but proved too large and cumbersome. 
Several hundred 4 and 8 ounce tins of the same shape were used in 
experimental plots. These proved more satisfactory. In canvass- 
ing the market for different types of tins available in quantity at a 
reasonable price it was found that the 4-ounce oblong spice tin with 
plain cover (fig. 11) met the requirements most closely. Such tins are 
crimped without solderings and are not water-tight at the seams. It 
was found that dipping these cans in paraffin of high melting point 
covered both the inside and outside with a thin, almost invisible 
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Fig. 12. — Method of paraffining spice tins for use in the field. 
coating, prevented leaking, and rendered them rust-resistant. (Fig. 
12.) One small hole was punched in a side about 1 inch below the 
top and the can hung by it on the tree over a 2d. finishing nail. 
These cans have proved the most satisfactory of all containers. 
They lie close to the trunks of the trees and are not moved by either 
wind or rain. When the ants are sluggish, as they are in cold weather, 
not uncommonly they cluster beneath the can and this doubtless 
increases their feeding. 
GROUND TRAPS. 
In control work about houses, especially where there are large 
lawns, and also in conservatories where water is freely used, water- 
tight round cans are advantageous. These are set in the ground along 
