CONTROL OF ARGENTINE ANT IN ORANGE GROVES. 15 



be set upon posts banded with the adhesive recommended on page 20, 

 to keep the ants out. The grove should be clean cultivated, from 

 March to September, by plowing and disking both ways of the grove 

 three or four times during that period. Even the cover crops should 

 not be grown during the first season of trapping, or until a very large 

 part of the ants have been destroyed. 



There should be at least 25 traps to the acre of 100 trees, and the 

 destruction of the ants will be accomplished much more rapidly if 

 twice that many are used. If 25 are used, one trap should be placed 

 near every other tree in each direction. For example, starting with 

 the first orchard row, set a trap near each of the first, third, and fifth 

 trees, etc., throughout the length of the row, then similarly in the 

 third, fifth, and seventh rows, etc. The traps should be located just 

 under the outer spread of the trees, where they will not be in the 

 way of the cultivator or so close to the tree that it will be injured 

 by the carbon disulphid gas. At a distance of about 4 feet from the 

 trunk the trap still will be on the tree hill and there will be no 

 danger of injury to the tree from the fumigant. The trap should be 

 placed upon a slight, level elevation made by throwing up and 

 smoothing off a few shovelfuls of soil. 



The number of covers necessary will depend upon the number of 

 traps and the conditions of labor. In experimental work with 415 

 traps, 48 covers could be operated most economically in fumigating, 

 as a crew of three could handle this number without loss of time 

 between setting and removing the covers. Therefore the proportion 

 of covers may be estimated roughly at 12 per 100 traps, or 3 per acre 

 of 25 traps, where 300 or 400 traps are used. 



In winter the traps should be filled with damp but not wet stable 

 manure and dry weeds or straw, the manure occupying the lower half 

 of the box. In summer the manure, which is used principally for its 

 heat, may be omitted. Maggots of the house fly, and perhaps other 

 insects which inhabit the manure, serve as an added attraction to the 

 ants. It is important to keep the lids always on the traps, to keep 

 out rain and darken the nest, and to help retain its warmth in winter. 

 As rain is by far the most important factor in driving the ants into 

 the traps, many more ants will be destroyed by trapping in summer 

 than in winter. 



METHOD AND COST OF FUMIGATING THE TBAPS. 



When the traps are full of ants and ready for fumigation the lids 

 are removed. 2 fluid ounces of carbon disulphid poured in, and the 

 covers slipped on and banked with soil, one shovelful being tamped 

 down at each side to help retain the gas. The traps must be fumi- 

 gated for one hour. Two ounces of carbon disulphid per trap of 1 

 cubic foot capacity, for oi.e hour, kills all stages of the ants in the 

 traps and for 3 inches in the ground beneath, as well as worms, sow- 

 buff's, etc.. inhabiting thp soil. 



