DNA barcoding of more than one million insect specimens indicates that at least one third of California's insect biodiversity remains undiscovered
Austin J. Baker, Brad Balukjian, Hilary Bayer, Jen Bayer, Daniel Gluesenkamp, Christopher C. Grinter, John M. Heraty, Amanda K. Hodson, Eva Sofia Horna Lowell, Colleen Kamoroff, Severyn Korneyev, Giar‐Ann Kung, Peter Oboyski, Leslie Saul‐Gershenz, Jayme E. Sones, Rebecca Stiling, Christiane Weirauch, Shayda Abidi, Elliott Allen, Rachel Allingham, Edeline Anthoniraj, John S. Ascher, Kelsey Bares, Julia G. Betz, J. R. Blair, Christina L. Boser, Christina M. Buck, Franklyn Cala‐Riquelme, Stephanie Castillo, Ellie Deer, Shahan Derkarabetian, Natalia von Ellenrieder, Lauren Esposito, Sara Fairchild, Glenn Fine, Brian L. Fisher, Glen W. Forister, Lorenzo Fraysse, Juan Grados‐Arauco, Laura Gaudette, Michael Gengo, Jacob Gorneau, Scott Hardage, Martin Hauser, Paul D. N. Hebert, Elizabeth H.T. Hiroyasu, Pam Horsley, Camille Hymes, Jacob Jones, Kevin L. Keegan, Peter H. Kerr, Emma Mathilde Kurstjens, Jesse Laine, Bethany Leach, Socrates Letana, Valerie Levesque‐Beaudin, Benjamin K. Maples, Martin Melia, Joe Miller, Christiana Mojica, Spencer K. Monckton, Denise C. Montelongo, Michael Nance, Michael W. Nee, Sarah Nguyen, Avas Pakrashi, Mikko Pentinsaari, Julia Perez, Diana Phan, S. Kennedy Pike, Kipp Pow, Nomena F. Rasoarimalala, Sujeevan Ratnasingham, Sylvia Reyes, Samantha Richey, Orlando M. Romeo, Cristina P. Sandoval, Ken R. Schneider, Michael Schweiker, Katja C. Seltmann, Michael J. Sharkey, Stevie L. Steele, Nathan Tang, Lauren Tham, Wil Valtakis, Matthew Van Dam, Elise Vasquez, Vanessa Verdecia, David L. Wagner, Michael A. Wall, P. Signe White, Jakob Woodall, Doug Yanega, Evgeny V. Zakharov, Megan Barkdull, Brian V. Brown, Laura Melissa GuzmanInsects are the most diverse terrestrial organisms, yet they are underrepresented in large‐scale conservation assessments. To address this gap, the California Insect Barcoding Initiative is developing a publicly accessible, statewide DNA‐barcode reference library for California insects to support scalable surveys, establish baseline biodiversity measurements, and generate potential distribution maps that inform conservation planning. Specimens are collected with a hybrid strategy that combines standardized Malaise trapping, to enable replicable sampling, and opportunistic collecting, to maximize taxonomic coverage. Using samples collected primarily from 2022–2024 at 72 longer‐term Malaise trap sites, coupled with collecting using varied methods at 454 additional locations across California, we have barcoded over one million specimens. Preliminary completeness analyses suggest that current sampling captures roughly 65–69% of the fauna, implying a conservative minimum of circa 61 000 insect species in California, as delimited by their DNA barcode sequence. Using all sequenced specimen records, we generated rule‐based spatial range interpolations constrained by ecoregion and vegetation type, and used these to infer spatial patterns in insect species richness across the state. We identify areas of both high and low potential species richness, with current peaks in the Southern California Mountains ecoregion and the Mojave Basin and Range ecoregion. Our species richness estimates and spatial patterns are explicitly provisional and are expected to evolve as sampling gaps are addressed. Finally, we make all sequence data, specimen images, and occurrence records publicly available via the Barcode of Life Datasystem. This ongoing effort constitutes the first large‐scale DNA barcode‐based survey for California insects, providing an expandable foundation for tracking temporal change, testing drivers of insect diversity, and prioritizing regions for conservation and targeted inventory.