60 BULLETIN 647, U. S. DEPARTMENT OF AGRICULTURE. 
The cost of the full treatment for the season was about 33 cents per 
tree. It is scarcely necessary to say that complete destruction of the 
ants would not bring about these results, nor did the ants in any 
degree prevent their attainment. 
EXPERIMENTS IN CONTROLLING THE ARGENTINE ANT. 
POISONING TESTS. 
In the poisoning work conducted against the Argentine ant in 
Louisiana the following 16 poisons were tested: Strychnine sul- 
phate, potassium cyanid, oxalic acid, arsenic trioxid. lead arsenate, 
Paris green, tartar emetic, oxid of antimony, mercuric chlorid, mer- 
curous chlorid. copper sulphate, sulphate of iron, chrome alum, 
sodium arsenite. chloral hydrate, powdered extract of belladonna. 
As 14 of them were given a thorough trial at three different strengths 
in the field, and 20 further tests were made on imprisoned colonies, 
there were 62 experiments in all. 
Methods of Conducting Poisoning Tests. 
The receptacle used for the poisoned sirup was a deep-shouldered 
fruit j ar of the type illustrated in Plate IV. with a tin lid with rub- 
ber band attached. A single entrance hole for the ants was punched 
in the center of the lid. To aid the ants in reaching the sirup, a 
piece of sponge was put into each jar. Scrap or waste sponges en- 
tirely suitable for this use may be purchased at wholesale drug 
stores for about 25 cents per pound. 
Upon beginning to forage at the poison, the ants would be traced 
to their nest and the location and size of the colony recorded, after 
which it would be watched and the effect of the poison noted. A 
definite amount of sirup, usually 4 or 8 ounces, was placed in each 
jar. every time, and the amounts taken by the ants thus learned. 
In poisoning tests on imprisoned ants each colony was confined 
to a low table supporting a three-celled Janet type plaster of Paris 
formicary, furnished with vent holes covered with bronze gauze. The 
ants were allowed to roam at will on top of the formicary and the 
4-inch margin between the sides of the formicary and the edge of the 
table. (See PI. IV.) To prevent ants from leaving the tables, the 
latter were placed in shallow galvanized-iron pans about 8 inches 
wider and longer than the table tops, containing a lubricating oil 
costing from 15 to 25 cents per gallon. The advantages of this oil 
were the extreme slowness with which it evaporates, its lack of an 
odor which might disturb the ants, and its nondrying property. 
Fresh sirup, cockroaches or other meat, and water were always at 
