Canopy invertebrates may reflect changes in tree structure and microhabitat that are brought about by human activities. We used the canopy fogging method to collect ants from tree crowns in primary forest, secondary forest, and pasture in a Neotropical cloud forest landscape. The total number of species collected was similar in primary forest (21) and pasture (20) habitats, but lower in secondary forest (9). Lower diversity in secondary forest was caused by lower species density (no. of species per sample). Rarefaction curves based on number of species occurrences suggest similar community species richness among the three habitats. This study has implications for conservation of tropical montane habitats in two ways. First, arboreal ant species density is reduced if secondary forest replaces primary forest, which increases the chance of extinction among rare species. Second, pasture trees may serve as repositories of primary forest ant communities due to similar tree structure.