Leinigen is the protagonist of this story, as he is the main focus of the rising action. There are few, if any, scenes not involving Leiningen and there is much more detail and information about him than anyone or anything else. He has the goal of saving his plantation but to do that, he must oppose the ants. The author shows Leiningen's goal to save the plantation when he is conversing with the Brazilian official. “Why, even a herd of surians couldn’t drive me from this plantation…” The main factor determining the protagonist is that it is his actions which control the course of the story. Also by describing Leiningen's thoughts and feelings the author shows he is the protagonist.

The ants may not be human, but there is no doubt that they are the antagonists of the story. The reason for this is that they are the main force against Leiningen in the story. An immense flood of ants, about a hundred yards in width, was pouring in a glimmering-black cataract down the far slope of the ditch. Many thousands were already drowning in the sluggish creeping flow, but they were followed by troop after troop, who clambered over their sinking comrades, and then themselves served as dying bridges to the reserves hurrying on in their rear. This is a fine example of how determined the ants are at getting to Leiningen and the plantation. The largest factor proving that the ants are the antagonist is that though the story would not exist without them, they are not actually the main focus of the story.