SAN FRANCISCO—From 1941 to 1943, the Xerces Blue butterfly species was last seen in the Presidio before dying out from habitat loss caused by urban development. In 1943, the Xerces Blue butterflies became extinct.
From 1990 to 2026, there have been 30 years of habitat restoration in the Presidio, including bringing back 50 acres of sand dunes and host plants like the deerweed (Acmispon glaber).
In 2021, California Academy of Sciences scientists mapped the genome of the extinct Xerces Blue using museum specimens to identify its closest, living relative.
On Monday, April 15, 2024, officials announced Silvery Blue butterfly (Glaucopsyche lygdamus), a surrogate species to the Xerces Blue started being released to the Presidio Dunes with the California Academy of Sciences collaborating with the Presidio Trust to make the effort happened.
On Tuesday, April 14, 2026, Presidio staff released more Silvery Blue butterflies near Rob Hill Campground. The goal of the project is to have a fully self-producing population over a 2 to 3 years period after the first 2024 release.
