Do army ants exist

With their feet, mostly. If they are moving from one "bivouac" (camp) to a new one, the workers carry the eggs and larvae (young ants, still grubs) in their jaws. They also carry the queen, some food, whatever they can carry. They are likely to attack and chop up any insects, Spiders and the like that they catch while moving. When they have settled in a bivouac, such as in a hollow tree, they send out columns of workers and soldiers to find food, such as stray insects or termites, that they bring back to feed the young and the queen.

For that reason people generally are glad when army ants show up; all you have to do is leave the house promptly, taking pets and babies with you, and stay out till they leave after a night or a few days. When you come back your house will be pest-free.

Some kinds of Army ants also eat small animals like lizards and mice that they catch, and if they find even large animals, some African species will eat them too if they can't get away, like if they are in cages or tied up, or babies in cribs. There are many kinds of Army ants in South America and different kinds in Africa.

When they are on the march, if they have to cross rivers and so on, they actually make bridges of their own bodies, chains of workers over which their companions can climb. Male army ants of most species can fly from one colony to another to mate.