THE ARGENTINE ANT IN RELATION TO CITRUS GROVES. 67 



bent into two right angles, forming two sides and the top, and two 

 pieces 13-1 by 13£ inches, forming the other two sides. The edges of 

 the latter two pieces are folded inwardly over those of the first piece 

 and hammered tightly together. Covers with soldered, instead of 

 hammered, seams are preferable, however, unless the latter are very 

 well made. The completed cover should measure 12| by 12£ by 12£ 

 inches inside, leaving a margin of £ inch to turn down all around 

 the outside to reinforce the open edge. 



Results of Ant-Tbapping Experiment. 



The experiment, the results of which are about to be briefly stated, 

 was conducted in a block of approximately 19 acres 1 of bearing 

 orange trees completely overrun with ants, located at Happy Jack, 

 La. The traps, numbering 415 in all, or about 22 per acre, were set 

 April 21-22, 1914. A trap was placed on a slight elevation at the 

 outer edge of the spread of every second tree each way, or one trap 

 to each four trees. Tests of various kinds of filler had shown pre- 

 viously that the best for summer was dry grass and weeds ; for winter, 

 equal parts of decaying manure and dry grass and weeds. From the 

 time of setting the traps until the first rain, about 56 days, the ants 

 were nesting almost wholly at from 8 inches to 1£ feet in the ground. 

 Even after such a period of prolonged drought, however, a rain of 

 about 0.2 inch, occurring June 18, 1914, was sufficient to drive them 

 into the traps in large numbers. 



Tests of different strengths of carbon disulphid and strong am- 

 monia water as fumigants proved that 12 ounces per trap of the 

 ammonia was satisfactory. The carbon disulphid, however, proved 

 satisfactory at as little as 2 fluid ounces per trap, allowing the traps 

 to fumigate for 1 hour. 



The first fumigation was started June 23, at which time it was nec- 

 essary to fumigate 334 of the traps, only those which contained large 

 and complete colonies being disturbed. The second, third, and 

 fourth fumigations were started July 21, August 26, and September 

 28, respectively, completing the summer's killing. A solid mass of 

 ants, in all stages, nearly as large as a man's hat, was killed in each 

 trap each time. The workers and even the queens were so numerous 

 that it was entirely out of the question to separate and count them in 

 any large number of the traps (see PL VI). The queens, however, 

 were counted each time in one or two traps with an average killing, 

 and in this way it was estimated that 1,161,323 queens were killed in 

 these first four or summer fumigations, 600,000 in the first two, 

 295,895 in the third, and 265,428 in the fourth. All of the traps were 



1 A11 references to the acre are to the "square acre," not the "acre front." 



