THE COLONY AS A WHOLE. 55 



various adverse conditions. During floods the ants will concentrate 

 in great numbers upon elevated ground, or many colonies will carry 

 their young stages up the same tree in order to get protection from 

 the rismg water. The most pronounced concentration, however, 

 occurs at the approach of cold weather in the fall, when large numbers 

 of colonies concentrate at one point to form the large winter colonies, 

 often consisting of hundreds of queens and many thousands of work- 

 ers. These colonies are fully described elsewhere. 



DIVISIONAL MIGRATION. 



Divisional migration is tlic opposite of concentrating migration, 

 and is always in evidence after a large number of ants have conce :- 

 trated at one place. It is most conspicuous in the spring, when the 

 large winter colonies break up into a great number of smaller ones. 

 These small colonies usually consist of one or more queens and a sup- 

 ply of workers. They distribute themselves in all directions from the 

 large colony, and locate in any place which affords suitable protec- 

 tion and an available food supj^ly. 



NESTS OR NATURAL FORMICARIES. 



Almost any place seems to be suitable for the location of nests of 

 the Argentine ant, provided that light and water may be sufiiciently 

 excluded. Some of the situations in which they have been found 

 are within hollow trees, beneath the rough bark of growing trees, 

 in forks of trees, in rubbish and compost heaps, in decaying logs and 

 timbers, beneath boxes and boards, under and in brick foundations, 

 in stored household goods, beneath shingles on roofs, in rolls of wrap- 

 ping paper, between walls of dwellings, in flowerpots, in piles of 

 brick and stove wood, in garbage cans, in bags of sugar, in birds' 

 nests, in discarded tin cans, in moss packing about the roots of nur- 

 sery stock, and in straw packing containing glassware or china, in 

 beehives with colonies of bees, under discarded tin roofing, around 

 the roots of cotton, corn, sugar cane, and other growing crops, in 

 railway cars, in various places on river steamboats and ocean-going 

 vessels, in old clothes, under street-car tracks, under brick and con- 

 crete pavements, in greenhouse benches, inside the husks of roasting 

 ears, inside of cotton boUs, in hollow hon electric-light posts, in the 

 cracks and crevices in telephone and telegraph poles, and in the cinder 

 baUast of railroad tracks. 



Most of the situations named are used as permanent nesting places 

 so long as weather conditions do not force the ants to find more 

 suitable quarters. With the advent of unfavorable conditions the 

 ants move their colonies with alacrity. 



