84 THE ARGENTINE ANT. 



Many preparations have been sold throughout the infested sections 

 for the purpose of destro^dng 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 aU remarkable that 

 such preparations have always yielded nothing but disappointment, 

 even though enormous numbers of foragmg workers were destroyed 

 by their use. 



EXPERIMENTS WITH POISONS. 



The use of poisons is generally the first measure suggested for the 

 destruction of an injurious insect, and experiments along this Hne 

 were begun by the senior author early in the course of liis investiga- 

 tions. An appreciation of the sahent features in the hfe liistory of 

 the pest soon emphasized the futility of using a poison wliich would 

 destroy the workers only. Any poison, to affect the rate of produc- 

 tion or to exterminate the species, must be one which \dU destroy the 

 fertile queens and the immature stages, aU of wliich are located witliin 

 the nest and are supphed with food by the workers. 



No way could be de^dsed by which poison could be administered to 

 the queens and larvae 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 tliis 

 hne but, incidentally, another and much more valuable use for poison- 

 ous mixtures was chscovered. 



Arsenate of lead, containing but Uttle arsenic in soluble form, 

 naturally suggested itself as the most promising substance for the 

 purpose. Accorchngly it was tried in various experiments, of winch 

 the following will serve to illustrate the results obtained: 



A mixture was made of 1 ])art pulverized sugar, 1 part paste 

 arsenate of lead, and 2 ])arts of honey. The ants carried this away 

 rapidly and on August 1 1 exhaustetl the entire amount that had been 

 put out. The su})ply was renewed, but on August 12 it remamed 

 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 tliis 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 



