54 THE ARGENTINE ANT. 



protected situations. This becomes more pronounced during the 

 latter part of November, and in the beginning of December we find 

 that the winter colonies with which we began are once more restored 

 and that large united colonies are the rule, with small colonies the 

 exception. 



COMPOUND COLONIES OR COMMUNITIES. 



Mention should not be omitted of the pronoimced manner in which 

 the social habit is extended beyond the limits of the individual nest 

 or formicary. During the summer season of activity, and in heavily 

 infested areas, communication between adjacent colonies is com- 

 monly observed. Not only the worker, but even fertile queens, 

 travel from one colony to another. So closely are adjacent colonies 

 associated in their activities that one can not do otherwise than con- 

 sider a heavily infested area as one enormous "compound colony" or 

 community. 



MIGRATIONS. 



Four distinct tyj^es of migration are exhibited by these ants, 

 without including the long trips which they take in columns to and 

 from the nests in search of food. 



GENERAL MIGRATION OR DISPERSION. 



By general migration is meant the slow but steady spread of the 

 ants from infested points into adjacent uninfested territory. This is 

 practically continuous, and while under natural conditions it may 

 amount to only a few hundred feet per year it is greatly accelerated 

 by artificial dissemination of the ants by man and his agencies. 



MIGRATION TO POOD SUPPLY. 



When the supply of food becomes scarce in the immediate vicinity 

 of a colony and a plentiful supply is discovered at a distance by the 

 foraging workers, movement of the colony in toto to the neighbor- 

 hood of the latter is not infrequent. Trees or jilants harboring large 

 numbers of scale insects are invariably surrounded by many po})ulous 

 colonies and the housewife who grows careless, permitting the ants 

 to get food in plenty within her domicile, is soon repaid by having 

 the ])remLses overrun with the pests. One can easily note this form 

 of migration by keeping a constant supply of honey or sirup in one 

 place for several days and providing a suitable nesting place — such 

 as a decaying log — near it. The latter is shortly occupied by one or 

 more colonies. 



CONCENTRATING MIGRATION. 



Concentrating migration takes place within the infested territory 

 and consists of the coming together of a large number of smaller colo- 

 nies to form a single large colony. This migration occurs under 



