84 THE ARGENTINE ANT. 
Many preparations have been sold throughout the infested sections 
for the purpose of destroying the ants. In nearly all cases these 
have been merely fluids which would kill the ants when coming 
in contact with them and the directions have stipulated that the ants 
should be sprayed with the solutions when on their foraging trails. 
In view of the foregoing statements relative to the small proportion 
of workers foraging at any one time it is not at all remarkable that 
such preparations have always yielded nothing but disappointment, 
even though enormous numbers of foraging workers were destroyed 
by their use. 
EXPERIMENTS WITH POISOXS. 
The use of poisons is generally the first measure suggested for the 
destruction of an injurious insect, and experiments along tins line 
were begun by the senior author early in the course of his investiga- 
tions. An appreciation of the salient features in the life history of 
the pest soon emphasized the futility of using a poison which, would 
destroy the workers only. Any poison, to affect the rate of produc- 
tion or to exterminate the species, must be one which will destroy the 
fertile queens and the immature stages, all of which are located within 
the nest and are supplied with food by the workers. 
Xo way could be devised by which poison could be administered to 
the queens and larvse except by having the workers carry it to them 
from sources of supply outside the nest itself. The problem therefore 
resolved itself into the search for some poison which would be fatal, 
but which at the same time would act so slowly within the workers' 
stomachs that they could transport it to the colony and there feed it 
to the inmates before perishing themselves. 
Some small measure of success attended our experiments in this 
hne but, incidentally, another and much more valuable use for poison- 
ous mixtures was discovered. 
Arsenate of lead, containing but little arsenic in soluble form, 
naturally suggested itself as the most promising substance for the 
purpose. Accordingly it was tried in various experiments, of which 
the following will serve to illustrate the results obtained: 
A mixture was made of 1 part pulverized sugar, 1 part paste 
arsenate of lead, and 2 parts of honey. The ants carried this away 
rapidly and on August 11 exhausted the entire amount that had been 
put out. The supply was renewed, but on August 12 it remained 
untouched. An examination of the nest was then made and it was 
found to be entirely deserted; the colony had moved away, taking 
with it all immature stages. That this action had been taken to get 
outside the sphere of danger from the poison there can be little doubt, 
for this colony had occupied the same spot for many weeks, despite 
the fact that it had been frequently dug open for examination and 
