From Packer, L. 2005. Species Profile: Halictus pinguismentus. In Shepherd, M. D., D. M. Vaughan, and S. H. Black (Eds). Red List of Pollinator Insects of North America. CD-ROM Version 1 (May 2005). Portland, OR: The Xerces Society for Invertebrate Conservation: Based on size variation among females, with larger females exhibiting macrocephalism, a long flight season (May-September), and a few ovarian dissections, this species is eusocial, with only mated queens overwintering, then provisioning at least one non-reproductive worker brood(s) before producing males and future queens in the late summer or fall. Lives in the foothills of the San Bernardino and San Jacinto Mountains in southern CA, USA
