CONTEOL OF ARGENTINE ANT IN CALIFORNIA. 43 



Trap nesting proved to be impractical under southern California 

 conditions because of the light average rainfall and the excessive 

 cost as compared with that of the use of a poisoned sirup. 



Repellents, in the form of corrosive-sublimate bands and powders 

 prepared from pyrethrum and sodium fluorid, were found to have a 

 limited use about residences, apiaries, etc. 



The most practical means of control was the complete eradication 

 obtained by the use of an arsenical poisoned sirup. Numerous 

 formulas were prepared and tried in large field experiments. Of 

 these the original Barber formula proved effective, but was objec- 

 tionable because of rapid crystallization. Various modified formulas 

 were used and one finally adopted which contained all the ingredients 

 of the Barber formula, somewhat reapportioned, and, in addition, 

 the preservative benzoate of soda. The modified formula gives a 

 much thinner sirup, one of greater stability, and also a considerably 

 cheaper one. The arsenical poisoned sirups have been used in 

 various parts of southern California on almost 3,000 acres of citrus 

 with excellent results. Ants have been totally eradicated from many 

 hundreds of acres with one or two applications. It is essential that 

 the sirup be carefully and properly prepared. 



Orchard control. — In orchard distribution approximately 1^ ounces 

 of sirup are placed in a 4-ounce spice tin with a few strands of excel- 

 sior, and such a tin is hung on the trunk or a main branch of each 

 infested tree. Spring and autumn are the preferred periods for 

 this work. Monthly inspection should be made and empty and 

 removed containers refilled and replaced. The average cost per tree 

 has been between 4 and 5 cents. 



Control about residences.— Thxs method has proved equally suc- 

 cessful in eradicating the ants about residences. Much care should 

 be given to bait each trail, at intervals of 10 to 15 feet, with either 

 a spice tin or a ground trap. 



The eradication of the Argentine ant has resulted in commercial 

 control of mealybugs and the soft brown scale over a large area in 

 the citrus districts of southern California. 



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