This study aims at documenting the use of nesting boxes by cavity-nesting bees and wasps in an urban environment to assess the role of these structures to pollination services at a local scale and as a tool for native pollinator conservation. We assess species preferences in terms of materials (logs or reed) and cavity diameter (narrow or wide). We compare colonization rate and species assemblages between three habitats: green alleys, community gardens and the Montréal Botanical Garden.