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 pronounced 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 workers, 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 types 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 FOOD 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 to to to the neighbor- 
hood of the latter is not infrequent. Trees or plants harboring large 
numbers of scale insects are invariably surrounded by many populous 
colonies and the housewife who grows careless, permitting the ants 
to get food in plenty within her domicile, is soon repaid by having 
the premises 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 
