On a small Australian island in the Indian Ocean, supercolonies of yellow crazy ants are causing what one biologist refers to as a "meltdown" of the native ecosystem. Gang of ants kill the island's iconic red land crabs by spraying them with formic acid; the crabs' annual migration, when millions of them scuttle to the sea, has been called one of the natural wonders of the world.

Recent research also showed that the ants swarm up plants and vines and bother birds trying to feed on berries, thus interfering with the dispersal of seeds around the island. The yellow crazy ant is considered one of the top 100 most invasive species in the world, and humanity hasn't yet found a way to turn the tide.

Status: They're Winning