70 years ago, a species called the yellow crazy ant (Anoplolepis gracilipes) turned up at the Christmas Islands off Australia, perhaps stuck to a piece of timber. For a long time, it remained dormant. Then in the mid 1990s, its population began to explode. Yellow crazy ants began to form super colonies, some as grotesquely large as 700 hectares (ha). The species swarmed the island, colonising