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Ant Troopers are large, blue ant-like enemies that appear in the Mario series. They have yellow eyes, red feet, and a pair of antennae. They attack by marching forward, sometimes appearing out of holes and Warp Pipes, and can walk along walls and ceilings. They are immune to Mario's stomp, but can be defeated with other attacks, such as ground pounds and projectiles. They are commonly found in groups, usually marching behind one another.
Two Ant Trooper variants also exist. Big Ant Troopers are, as their name suggests, larger Ant Troopers that are immune to any attack. Another variant, the Horned Ant Troopers, have spiked helmets on their heads, and as such cannot be jumped on.
Though they do not appear in Super Mario and the Underworld Trials, Ant Troopers and Horned Ant Troopers appear as enemies in The Rescue Squad: Birthday Blitz as enemies featured in Honeyhive Elementary. They act exactly like their appearance in Super Mario 3D World, continually marching forward. They are still immune to jumps, though punches and kicks can defeat them.
Ant Troopers and Horned Ant Troopers reappear in Mario & Luigi: Sage Quest as enemies fought in Fort Fossil with other enemies Hammer Bros., Boomerang Bros. and Chargin' Chucks. Horned Ant Troopers appear in battle, and Ant Troopers appear when they take enough damage (or at the start of a battle) with lower defense. They can also appear in large groups if any other enemy does not appear in battle. Horned Ant Troopers attack by hopping into the air to headbutt Mario and Luigi, which needs to be countered with a hammer, while Ant Troopers attack by simply ramming into them. If the number of Ant Troopers and Horned Ant Troopers in battle combined is a multiple of three, they will attack the Mario bros by dashing towards them in groups of three.