Arboreal earthworms are scarce in tropical rain forests, being confined to tree trunks or epiphytes (Fragoso & Rojas-Fernandez 1996). Their above-ground presence might be attributed to (1) temporary responses to flooding (Adis & Righi 1989), (2) permanent responses to acidity, flooding and anoxia of very wet forest soils (Lee 1983), (3) drought (Fragoso & Rojas-Fernandez 1996), (4) accidental events, e.g. mudslides (Picado 1911), or (5) anti-predation responses, e.g. escape from army ants (Gotwald 1995).