Abstract Most canopy insect research takes place in tropical forests, where communities are highly vertically stratified. However, temperate forest canopies also provide critical resources to many species and are under intense pressure from global change drivers. The relative lack of knowledge regarding temperate canopy insect ecology impedes our forest management and conservation decisions such that we may be losing temperate canopy biodiversity before we know it exists. We directly compared ant diversity and community composition on the ground and in the tree canopy of North American temperate deciduous forests for the first time. We also evaluated two canopy sampling methods—baits and hand collections. We collected 34 ant species from 102 trees across seven sites. Ant diversity was greater on the ground than in the canopy, and species turnover created distinct communities across vertical strata. Only 12% of species were exclusively arboreal, but 47% were collected in both strata, indicating the canopy is an important resource for temperate ants, even if they are not restricted there. Baiting and hand‐collecting recovered similar species richness, but whether baits captured a subset of hand‐collected species or a unique assemblage was site‐dependent. Nevertheless, we suggest that these methods are most effective in conjunction. Hand collection allowed us to document arboreal nests of 10 species, including the invasive needle ant, Brachyponera chinensis , which was previously thought to be strictly terrestrial. Our results emphasise the importance of including the canopy in temperate forest ecology and conservation assessments.