52 THE ARGENTINE ANT. 
When the temperature falls as low as 60° F. the ants become 
sluggish, and foraging is largely suspended. At from 50° to 55° F. 
there is practically no foraging, and when this temperature is reached 
within the nest all adult ants become inactive, moving only occasion- 
ally, and even then with apparent difficulty. Activity is not strictly 
limited by these temperatures, however. On one occasion we found 
workers foraging in a building the interior of which was at 43° F., 
but the colony itself was outside the building and at a higher tem- 
perature. Very few refrigerators are cold enough to keep out these 
invaders when the outside temperature is warm enough for them to 
forage normally. On the very hottest days of summer they will 
enter refrigerators and even crawl into the ice chamber itself in order 
to reach some much-desired delicacy. 
The most ideal location for the large winter colonies is in piles of 
decomposing vegetable matter. This material gives off a large quan- 
tity of heat during the process of rotting and consequently furnishes 
the ants with automatically heated apartments. In the same manner 
in which the ants seek optimum humidity conditions during the 
summer months, so they will regulate their location to preserve an 
even temperature in their nests in the winter. In cold weather they 
will carry the young stages toward the center of the piles, while in 
warmer weather they will be found near the surface. 
Of course all the ants are not able to find ideal locations for the 
winter months, and great numbers have to locate themselves as well 
as they can. In open fields great numbers will be found under large 
ridges, or along ditch banks, particularly those which have a southern 
exposure. Many will burrow into the ground at the bases of large 
trees, where their tunnels and galleries will sometimes attain a depth 
of 12 to 14 inches. 
Under Louisiana conditions the winter colonies are in evidence 
during the months of December, January, and February. The segre- 
gating tendency becomes marked during November, and the "divis- 
ional migration" normally occurs in February, but may not take 
place until March if the spring is cold and wet. 
SUMMER COLONIES. 
As soon as the weather gets warmer in the spring and food becomes 
abundant the large winter colonies break up into a great number of 
smaller colonies. These usually consist of one or more queens and a 
considerable number of workers, and they establish themselves in 
any good location wmere a supply of food is available. In places 
where food is exceptionally abundant these summer colonies will still 
remain very strong in numbers. Under large magnolia or oak trees, 
for example, colonies with 10 or 20 queens and many thousand 
workers are nearly always present. 
