62 BULLETIN 647, U. S. DEPARTMENT OF AGRICULTURE. 



The poisons which came through both tests with the best record 

 were : 



(1) Chloral hvdrate, 3 gm.. to sirup. 120 gm. 



(2) Sodium arsenite. 0.143 to 0.287 gm., to sirup, 120 gm. 



(3) Arsenic trioxid, 0.125 to 0.250 gm.. to sirup, 120 gm. 



(4) Lead arsenate, 1.0 gm.. to sirup, 120 gm. 



(5) Tartar emetic, 0.525 gm., to sirup 120 gm. 



By far the most rapid and successful of all was the chloral hydrate 

 mixture. 



POISOXING ASTS I>* THE ORANGE GbOVES. 



Two experiments were conducted in an attempt to destroy the ants 

 in orange groves by means of poisoning. One of these, in which the 

 trees were not banded and weeds were allowed to flourish during 

 the experiment, failed to have any appreciable effect upon the ants. 



In the other one a plat of 237 orange trees was first completely 

 isolated from the rest of the orchard by means of barrier ditches. 

 All weeds and trash were then removed from the plat, and the trees 

 all banded with an adhesive mixture, thus limiting the food supply 

 for ants within the plat to the poison and a comparatively few rotting 

 oranges, dead insects, and fiddler crabs. The ground in the plat was 

 almost covered with a mass of ants, there being 250 " very large," 

 " large." and " small " colonies, or more than one for every tree. 

 The ants took the poison intermittently, attendance being abundant 

 at certain jars at one time, at others the next, and attendance at the 

 poison was no doubt greater than it would otherwise have been be- 

 cause of the scarcity of food. 



The result of the poisoning and tree banding together was to re- 

 duce the ants after about four months to 2 " large r " and 17 " very 

 small " colonies. On ordinary inspection and comparison with the 

 adjoining plat one would say that there were no ants left in the 

 treated plat. The poison, in itself, was not a marked success, how- 

 ever, as cutting off the food supply had caused fully 75 per cent of 

 the ants to migrate, as shown by the speed with which the first large 

 disappearance of ants took place, and the frequent occurrence of 

 thousands of dead ants on the water in the ditches. 



USE OF TREE-BAXDING MIXTURES. 



It seems doubtful whether adhesive and other repellent mixtures to 

 be applied to the trunks of the trees will ever be used extensively as 

 ant barriers in Louisiana orange groves. Such barriers do not reduce 

 the ant population and can not be considered as a positive means of 

 control. When used on a large scale bands of this sort need more or 

 less frequent inspection and renewal or respreading. and the cost of 



