The Argentine ant has conquered the globe by abandoning its own natural instincts.

Nature · Published 3 October 2026 Swipe more like this →

In short: While most ant species are fiercely territorial, the invasive Argentine ant thrives by ignoring its own kind. By forming massive, non-aggressive supercolonies that span entire continents, these ants have outcompeted native species and disrupted ecosystems worldwide. Their secret to global domination is a surprising lack of internal conflict.

Native to the Paraná River drainage in South America, the Argentine ant (Linepithema humile) has become a globally distributed pest. Unlike their South American counterparts, which remain genetically diverse and territorial, introduced populations have undergone a behavioral shift. In their invaded range, these ants exhibit unusually low levels of intraspecific aggression. This lack of hostility allows them to merge into vast supercolonies where individuals from different nests mingle without conflict, enabling them to achieve population densities far higher than those found in their native habitat.

The scale of these supercolonies is unprecedented. A single massive network in California, stretching from San Diego to beyond San Francisco, was estimated to contain one trillion individuals as of 2010. These supercolonies are so expansive that researchers have compared their reach to human society. While they generally cooperate, they are not entirely peaceful; boundaries between different supercolonies can become permanent battlefronts. In San Diego, the border between the 'Very Large Colony' and the 'Lake Hodges Colony' sees thirty million deaths annually, with fighting occurring ceaselessly unless interrupted by weather.

This success is partly driven by how the ants recognize kin. Research suggests that dietary factors influence the hydrocarbons on an ant's cuticle, which serve as identity cues. Ants with similar diets recognize each other as family, while those with different food sources may trigger violent reactions. Beyond their social structure, these ants are economic threats because they protect honeydew-producing pests like aphids and mealybugs from natural predators. This mutualism can reduce the effectiveness of biological pest control, such as parasitoid wasps, by up to five-fold in citrus crops. Because they nest in shallow, protected areas like potted plants or brickwork, they are notoriously difficult to eradicate with standard insecticides.

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