Omalus puncticollis was earlier considered as a synonym to Omalus aeneus. However, results from DNA-barcoding indicate that O. puncticollis is a good species. It is generally rare, but locally common in eastern Norway where it occurs in shrubs and warm slopes with large amounts of dead wood. The hosts are small species of wood living Crabronidae of the genus Passaloecus. The species can be distinguished from Omalus aeneus by the more strongly punctured mesoscutum with long setae.