Yes, ants most certainly do fight each other. The world of ants is one of conflict and fierce battles. They wage small-scale fights to all-out wars with each other. In fact, fossil evidence suggests that ants have been fighting for at least 99 million years. 
In this article, we’ll learn more about ant fights as we discuss the following:
- Types of ant fights
- Why do ants fight each other
- How do ants fight each other
Types of Ant Fights: Who Do Ants Fight With?
Ant fights can be external or internal. External fights include ants from different colonies fighting each other. These usually happen with worker ants due to competition for resources.
Internal fights, on the other hand, involve ants from the same colony. These may include ants within the same or different castes. For example, queens may fight with other queens or their workers.
Why Do Ants Fight Each Other?
There are a number of reasons why ants fight. Some of these reasons hit close to home as they’re very similar to what causes conflict between us humans. They are as follows:
The most prevalent cause of fighting between ants is competition. Ant colonies that nest close to each other fight for valuable resources such as food.
Due to competition, some ants invade the nests of rival colonies to try and take over their food sources. When this happens, the nest inhabitants fight to defend their homes from the invaders.
Ants don’t only fight ants from other colonies, they also fight among themselves. For instance, ants may sometimes assassinate their queen when its reproductive capability deteriorates. This allows them to put up a stronger queen as a replacement and increase the chance of colony survival.
See this article to learn what happens when the queen ant dies.
Some queenless ants kill each other to prevent overpopulation. Any ant which lays eggs in unideal times gets killed off.
This is to make sure that they can accommodate the colony’s needs and that they don’t run out of resources. 
There are many ant colonies that have a polygynous social structure. Instead of only one, these colonies have many queens that share the reproductive load. See this article to learn more about polygynous ant colonies.
Sometimes ants simply fail to recognize their nestmates and mistake them for enemies. This occurs when ants pick up the wrong odor cues from their nestmates. This then elicits an aggressive reaction which leads to fighting. 
How Do Ants Fight Each Other?
One might imagine that ant fights are simple contests of force and numbers. But while that’s partly true ant fights can be far more complex. Ants can make use of different weapons and strategies to beat their competition.
Ants naturally possess physical weapons that they use for fighting. For example, they have strong mandibles which they use to bite and tear their enemies into pieces. Some ants also have stingers at the end of their abdomens which they use to pierce.
Ants also use make use of chemicals to attack and defend themselves. Some ants, for example, can spray formic acid from their abdomens to poison their enemies.
An extreme example of chemical use comes from the species Colobopsis explodens.
These ants lack large mandibles and stingers and are thus seemingly harmless. However, these ants can blow themselves up and release sticky, bright yellow toxins. 
Ants also fight smartly. They don’t run around mindlessly chomping their mandibles and spraying formic acid. Instead, they make use of strategies and coordinated attacks.
For example, a common strategy that they employ is grouping up to pin down their enemies as they tear them apart. Brutal, yet somehow also impressive.
Ants have also been likened to Roman armies. They sometimes attack their enemies by surprise as one massive battalion. They position expendable ants on the front line and let stronger ones stay behind. When the enemy ants are exhausted, they release their stronger fighters to go for the kill. 
Apart from wars, ants interfere and disrupt each other as they fight over resources. For example, the ant species Novomessor cockerelli is known to disrupt competitors by filling their nests with sand. This delays the activity period of the latter by up to 3 hours and decreases their foraging capacity. At the same time, the former gets to forage with less competition. 
Make Love, Not War
With a very long history of fighting, it may seem unlikely for different ant colonies to get along. Yet that’s exactly what happens.
Ants that have been fighting to the death can suddenly stop fighting and form a lasting truce. This occurs even as the queens of each colony are still alive. 
This prevents more costly deaths that may leave even the victor vulnerable. It allows them to refocus on defending the territory from other external threats.
To summarize, ants fight each other. They wage wars with other colonies for resources. They also fight internally due to politics, population control, and miscommunication.
All in all, they have it rough. Competition and fights are simply part of their daily struggle. Encounters with rival colonies may take hundreds to thousands of lives.
But that’s not the only issue. Internal fighting may sometimes lead to the death of all queens and thus the death of the colony itself.