THE ARGENTINE ANT. 
INTRODUCTION. 
The Argentine ant (Iridomyrmex humilis Mayr) , which is made the 
subject of the present paper, is the first among the Formicidse to attain 
the front rank among injurious insects in the United States. In its 
field the Argentine ant is not excelled in destructiveness by even the 
gipsy moth, the boll weevil, or the San Jose scale. Though this ant 
is limited as yet to comparatively small areas, the observations and 
experience of the authors fully convince them that future years will 
see this insect steadily invading new territory and forcing its depre- 
dations upon the inhabitants of all southern California and most of 
the Gulf States. 
The present paper aims to present, in as concise a manner as possi- 
ble, the principal results of five years of almost constant observa- 
tion and experiment by the senior author at Baton Rouge, La., and in 
the orange-growing section of the same State, together with observa- 
tions made by the junior author at New Orleans in connection with 
his investigations of sugar-cane insects. 
The junior author has prepared in their entirety the portions deal- 
ing with the " Area of ultimate infestation," and the " Relation of the 
ant to Coccidse and Aphididse," and to him is also to be credited the 
important discovery that mating of the queens may occur within 
the formicary or nest of the colony. The remainder of the paper, 
except where otherwise noted, is compiled from the notes and records 
of the senior author. 
In the tedious work which accompanied the determination of the 
ant's life history, from 1907 to 1910, much assistance was rendered 
by the young men associated with the senior author in the work of 
the Louisiana State Crop Pest Commission, particularly Messrs. 
Harper Dean, A. H. Rosenfeld, G. A. Runner, M. S. Dougherty, 
G. D. Smith, and R. C. Treherne. 
The writers are under obligations to Dr. W. M. Wheeler, of the 
Bussey Institution, Harvard University, for permission to use his 
redescription of Iridomyrmex humilis and for his kindness in reviewing 
the paragraphs upon "Systematic position" and "Resemblance to 
other ants." 
Our thanks are also due to Messrs. R. S. Moore and John Meyer, 
extensive orange growers of Louisiana, for their liberal cooperation 
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