S1, E5: Some invertebrates have overcome the limitation of their small size by banding together in huge numbers. Many of these societies are so fine-tuned in the way they operate it's as if they were a single being. But insect societies aren't all shining examples of co-operative behaviour. The series ends with two insect armies fighting head on as Matabele ants raid a nearby termite mound. The result is total carnage.