Phylogenetic distribution of snail shell nesting in osmiine bees. Red = taxa that probably exclusively consist of obligate snail shell nesters; blue = taxa that contain both obligate and facultative snail shell nesters (in Hoplitis (Anthocopa), only one (exclusive) snail shell nester is known); green = taxa that probably contain only facultative snail shell nesters; black = taxa that do not contain any snail shell nesters to the present knowledge (nesting biology of Hoplitis (Megahoplitis), Hoplitis (Platosmia), Wainia (Wainia), Wainia (Wainiella) and Osmia (Nasutosmia) still unknown). sp. gr. = species group. Phylogeny based on Praz et al. (2008a), Rightmyer et al. (2013) and Sedivy et al. (2013a).