Ants are believed to regulate herbivorous insects in the canopy of tropical rainforests but few studies have empirically investigated the anti-herbivore effects of the ants there. We examined the anti-herbivore effects of the ant species Crematogaster difformis which territorializes a large area of the crown of emergent canopy trees and inhabits the myrmecophytic epiphytes Lecanopteris sp. and Platycerium sp. which grow in the crown by performing an ant-exclusion experiment in the field. The average proportion of leaf area loss the proportion of damaged leaves and the proportion of leaves with ‚â•50% leaf area loss were all significantly higher on experimentally ant-excluded branches than on ant-attended branches at 3 months from the beginning of the ant-exclusion treatment. These results suggest that C. difformis regulates not only herbivorous insects that potentially feed on its host epiphytes but also those that could feed on leaves of emergent canopy trees that harbor the epiphytes.