Trophobiosis are common tri-trophic trophic interaction between plants, sap-sucking insects and ants. While sap-sucking insects directly exploit plants in a cryptic form of herbivory, the ants establish a mutualistic relationship with the sap-sucking insects: in exchange for honeydew ants protect their partners against predators and parasitoids. Such interactions can be abundant in forest ecosystems and contribute substantially to fluxes of matter and energy in these ecosystems. The present overview illustrates the key characteristics of trophobiosis and gives examples of Hemiptera and ant species regularly found in the BEF-China main experiment.