THE ARGENTINE ANT IN RELATION TO CITRUS GROVES. 61 
hand on the table, in addition to the poison, in order to approximate 
field conditions as nearly as possible. With this apparatus and 
method of feeding, ant colonies have been kept in a state of health 
for nearly two years. In some cases, where the ants are confined for 
prolonged periods without flesh food, they feed upon their own eggs 
and young. 
Summary of Results of Poisoning Tests. 
In conducting tests on nonimprisoned ants, difficulty was experi- 
enced in determining the effect of the poison upon the ant colony. 
Desertion of the nest may mean that the ants have been destroyed, 
that the poison has merely impelled them to move, that they have 
moved from need of better quarters, or that they have discovered 
more abundant and suitable food elsewhere. The colony may move 
slowly from the immediate neighborhood of the poison, but its scouts 
continue to hang about the latter indefinitely. It may remain where 
it is and follow the original trail near the poison without visiting it. 
Slow migration may occur, giving the impression that the colony 
is being destroyed, when such is not the case. From 26 to 298 days 
were required to bring out the results. If the poison dosage is too 
strong, the ants will leave it before much harm befalls them; if so 
weak as to assure continuous feeding, its action is extremely slow. 
The amounts of poisoned sirup consumed by the ants in field teste 
varied from as low as 0.04 ounce per day over a period of 189 days 
to as high as 1.2 ounces per day for 296 days. Dead worker ants 
were found in or near the poison jars only in the case of three of the 
poisons, viz, strychnine, potassium cyanid, and arsenic. Large 
numbers of dead ants occurred often only at the jars containing 
potassium cyanid. 
The poisons selected for a final testing upon imprisoned colonies 
were strychnine, potassium cyanid, arsenic trioxid, lead arsenate, 
mercuric and mercurous chloricl, tartar emetic, sodium arsenite, 
chloral hydrate, and belladonna. The first symptoms of poisoning 
shown by the imprisoned colonies are a strong desire on the part of 
the workers for water and assiduous cleansing of the body, par- 
ticularly the jaws. An ant will commonly regurgitate a dose of 
poison, and a sister worker will cleanse her distended jaws with 
great thoroughness, repeatedly going over them with the mandibles 
and tongue. The next effect upon the colonjr is generally the death 
of some of the young, followed by a slackening, and finally a cessa 
tion of oviposition. The young then die rapidly, followed by work- 
ers, until all of both phases are dead. The queens then begin to do 
their own foraging, and finally succumb to the poison, at times not 
until several days after the demise of the last worker. 
