[1] Research based on four nuclear genes (elongation factor-1α F2 copy, long-wavelength rhodopsin, wingless and the D2–D3 regions of 28S ribosomal RNA—2700 bp in total) suggests the historical view of family relationships need to be changed, with Rhopalosomatidae as a sister group of the Vespidae and the clade Rhopalosomatidae + Vespidae as sister to all other classical vespoids and apoids.

Their research also found families Mutillidae, Tiphiidae, and Bradynobaenidae to be paraphyletic.

[2] A later study in 2013 confirmed the need for revision of high-level relationships, and the pattern of sister-group relationships within the putative Vespoidea largely matched the same basic pattern as the 2008 study.

[3] The extinct family of Armaniidae also was formerly considered to be a group of "ant-like wasps" and was also classified under Vespoidea.

[4][5] However, additional work by Borysenko in 2017 found these species to be basal members of Formicidae, placing three genera under Sphecomyrminae and considering the rest incertae sedis.