Thread by @Paracelsus1092

The Argentine ant global set of supercolonies is one of the largest cooperative societies on earth, it is also one of the most aggressive. World war ant has been raging for over a century, from Japan to South Africa.

But where did it all begin? 🧵

Argentine ants (Linepithema humile) are about 2.5mm in size, native to Argentina, and considered an opportunistic, flexible and aggressive species. Within their native range their genetic diversity is wide and different colonies regularly fight each other.

However, outside of Argentina their genetic diversity is extremely low, and often entire continent's worth of Argentine ants can be traced back to a small number of individuals. Despite living in separate colonies these ants recognise one another as kin, and do not attack.

The result of this is that invasive colonies of Argentine ants form peaceful 'supercolonies', capable of dominating huge areas of land. One of the largest we know of is called the Very Large Colony, stretching from San Diego to San Francisco, with maybe one trillion members.

This colony formed over a century ago, when ants were accidentally transported from Buenos Aires in the 1890's to Louisana on steamboats and then California, likely by train. Their internal cooperation and externally directed violence has made them unstoppable.

They eat seeds, farm aphids for honeydew and destroy other ant's nests for food. Seed-harvester ants have been known to plug up their entrances to prevent Argentine ants entering, but they will wait and starve them out, launching waves of assaults until they decimate the nest.

The Very Large Colony has one major rival supercolony - the Lake Hodges colony - which is separated by several freeways. In 2004 researchers realised that 30 million ants a year were being killed on the borders between the two colonies, ants fighting over the bodies of their dead

The battlefields between the colonies can stretch for miles, places where ants wrestle with one another for unknown amounts of time, ripping off legs, antennaes, heaping up corpses and shifting backwards and forwards as territory is won or lost.

California has been won by the Argentine ants, and the Very Large Colony control the port cities of Richmond, Oakland, San Francisco, Long Beach, Los Angeles, and San Diego. This is important because they have used the ports to spread across the world, exploiting the sea lanes.

We'll look at this in the next thread - the global dominance of the Argentine ants by use of the global shipping system. We'll also see how other ants are fighting back against this intrusion - welcome to world war ant!