According to Webster's dictionary, army ants are “any ants that go out in search of food in companies, particularly the driver and legionary ants”. Scientists once thought that army ants migrated whenever they ran out of food. Studies now suggest that the ants have a regular cycle of traveling and nesting. The scientists suspect that the cycle of migration and nesting is linked with the development of the immature ants in the colony.
There are several species of army ants. They are found in Africa, Asia, Australia, Central America, and South America. They seem to live in warm, tropical areas. Many species of army ants live in jungles or heavily forested places. The ants might live in these places so they can find a steady supply of food.
Many army ant species live in very large colonies. Eciton burchelli colonies can have as many as 700, 000 members. Scientists suspect that colonies of Labidus praedator can contain over a million ants. Large groups of ants require large amounts of food.
Army ants spend a few weeks in a stationary or nesting phase. They stay in one nesting site for two or three weeks. The queen produces thousands of eggs during this period. The workers care for the eggs and the immature ants that are developing.
When new adults come out of their cocoons, the colony quickly goes into a migratory phase. For two or three weeks, the anis move in columns. Some of the workers carry eggs and immature ants. Most of the workers march side-by-side. The columns move at a rate of about 20 meters (about 60 feet) per hour. The workers gather anything that the colony can eat – insects, birds, lizards, small animals, and even fruits and nuts.
During this migratory phase, the column makes a new bivouac every night. The workers make a temporary nest inside hollow logs, under fallen trees, at the bases of trees, under piles of leaves, or even in branches of trees. Many times the workers will make a shelter with their bodies to protect the queen and the immature ants from the weather.