Five fire ant species are colonising the world – stowing away on international shipping. Now they are slugging it out amongst themselves for world domination.

Fire ants are tolerant of individuals from other nests of their species. So they really do form empires stretching for miles: even thousands of miles. A single supercolony, possibly descended from as few as half a dozen queens, now stretches along 6,000 kilometres of coastline in southern Europe. Another runs most of the length of California.

Once they arrive, the effect on all forms of life (including us) are enormous and invariably harmful, upsetting the local ecology by driving out other ant species and out-competing or conquering other insects. They attack lizards and other small vertebrates, and strip trees of leaves. This last behaviour is indirectly having a serious effect on lion populations in Kenya.