A classic case of myrmecotrophic mutualism

In the association between the carnivorous pitcher plant, Nepenthes bicalcarata, and Camponotus schmitzi ants in Borneo, the ants benefit by getting food and nesting space. In return C. schmitzi ants regularly clean the pitcher rim (peristome), which is the main surface used by the plant for prey capture. This behaviour increases the carnivorous plant’s prey capture efficiency. It also helps the plant to keep the pitchers effective over long periods of time.

Journal reference

Setting the trap: cleaning behaviour of Camponotus schmitzi ants increases long-term capture efficiency of their pitcher plant host, Nepenthes bicalcarata

Daniel G. Thornham,Joanna M. Smith,T. Ulmar Grafe and Walter Federle , Functional Ecology, Volume 26, Issue 1, pages 11–19, February 2012