Leaves of the giant leather-fern, Acrostichum danaeifolium, were infested by larvae of an unknown species of moth (microlepidoptera) at a mangrove site on the Gulf of Mexico. During a nine-month observation period these moths infested 87% of the ferns and 41% of their leaves. The damage caused by the moth larvae consisted of galleries bored into the petioles and rachis; however, this did not affect maximum leaf size. The galleries form a microhabitat that later can be colonized by ants. Among ten ant species found, two introduced tramp species, Tapinoma sessile and Wasmannia auropunctata were the most common ones. Because it does not produce domatia or extrafloral nectaries to attract ants directly, the giant leather-fern becomes an involuntary myrmecophyte by harboring ants in the moth-constructed galleries.