10 THE ARGENTINE ANT. 



and assistance in experiments carried out in the infested orange 

 districts. 



GENERAL CONSIDERATIONS. 



Twenty years ago the Argentine ant was first noticed in New Or- 

 leans, La., by Mr. Edward Foster, reference to whose interesting 

 account of the "Introduction of Iridomyrmex humilis Mayr into New 

 Orleans" will be found on a subsequent i)age. The species had 

 doubtless been introduced years before that time, but was gathering 

 strength and establishing itself for a considerable period before its 

 numbers became sufficient to attract attention. Mr. Foster men- 

 tions it as occurring in 1891 in "fair numbers." Smce then it has 

 increased from a few scattered and apparently msignificant speci- 

 mens to armies and hordes numbering myriads of individuals. It 

 has spread from a few blocks on the water front of the Mississippi 

 River over practically the entire city, and has sent out vast numbers 

 of colonists for hundreds of miles along the railways and waterways 

 radiating from New Orleans. These pioneers have succeeded in 

 founding scores of communities of more or less importance in the 

 smaller cities and towns. Each of these communities is in turn 

 furnishing its quota of migrants, and these are extendmg the affected 

 territory in all directions from the original source of infestation. 

 Thus, instead of the dispersion being from one source only, it is now 

 taking place from hundreds of different points. From an unknown 

 and little noticed insect this ant has developed into one of the fore- 

 most household pests in the world, and its ravages affect, directly or 

 indirectly, the majority of the crops grown m the South. Former 

 indifference to its movements has given way to concern at its approach, 

 which, in tlie orange belt at least, means heavy depreciation in the 

 value of property. 



Continuous study for several years has served to enlighten us on 

 most of the salient features in the life history and economy of the 

 species. A considerable number of poisons and repellents have been 

 tested and have given good results. Methods of isolating, ditching, 

 and winter-tra})ping have been devised, and liave proved their prac- 

 tical value in large experiments under field conditions. 



Just how much territory this ant will ultimately infest we can not 

 foretell with accuracy from the data at present available. It is 

 quite safe, however, to venture the opinion that the species will 

 eventually spread over a considerable portion of the Southern States — 

 certainly over all of the orange and sugar-cane belts, and perhaps over 

 all of the cotton belt. In California it is likely to cover the territory 

 corresponding in temperature to the belts mentioned for the South, 

 which will include the belts occupied by oranges and other tender 

 fruits. 



