關於an overview of fire ant variants in the Fallout series of games，參見fire ant。 關於an overview of giant ant variants in the Fallout series of games，參見giant ant。
Fire ants are creatures living in the Capital Wasteland in 2277. They are a variation of giant ants that have been genetically modified, and their name comes from their ability to expel a flammable acid from their mandibles.
Fire ants have a hard, red-orange carapace that protects their body from most environmental factors. They live in enormous underground colonies where they eat, sleep, and mate with the queen. Fire ants are omnivorous, either using their pyrosis to hunt and kill prey, or eating what little vegetation they can find, when necessary.
Fire ants like to attack from range with a fire breath attack, which has a surprisingly long effective range. The ants seem to have a minimum range at which they can breathe fire. If a character gets extremely close to the ants, they will constantly try to move backwards, letting off a spurt of flame or two. Additionally, they have a slow turn speed.
If their antennae are crippled, they will become frenzied. Once a fire ant becomes frenzied, it will attack other nearby fire ants and other non-player characters. Once attacked by another ant, the attacked ant will defend itself, damaging the attacking ant. When the frenzied ant kills something, the player character gains the appropriate Experience Points for that kill.
Fire ant soldiers are the second lowest ranked ant in a fire ant colony. Their job is to protect their area from intruders. They are very aggressive and will attack humans, as well as other creatures, on sight. They are relatively easy to defeat at medium levels or with a well-equipped low level character.
Fire ant workers are the backbone for the ant community's infrastructure. As the name implies, they dig tunnels and care for the eggs. However, they will attack intruders if they are threatened. They are much weaker than any other variant.
This ant queen is found in the queen ant's hatchery. Like the others in the game, she is slow and has a ranged acid spitting attack that does a fair amount of damage. She cannot spit fire because Doctor Lesko's experiment affected only her eggs. The queen has a very high amount of HP and is considered a "boss" enemy in the game.