|Samples of the extinct Glaucopsyche xerces butterfly in the collections of the Field Museum of Natural History|
The Xerces blue (Glaucopsyche xerces) is a recently extinct species of butterfly in the gossamer-winged butterfly family, Lycaenidae. The species lived in coastal sand dunes of the Sunset District of the San Francisco Peninsula in California. The Xerces blue is believed to be the first American butterfly species to become extinct as a result of loss of habitat caused by urban development. The last Xerces blue was seen in 1941 or 1943 on land that is now part of the Golden Gate National Recreation Area.
The specific name derives from the French spelling of "Xerxes", the Greek name of the Persian kings Xerxes I and Xerxes II of the fifth century BC. An endangered invertebrate conservation group known as the Xerces Society is named after the Xerces blue.
Extinction and ecology
The species was first described and documented in 1852. It was characterized by blue wings with white spots. The butterflies fed on vegetation belonging to the genus Lotus and Lupinus. The loss of the Lotus plant that the butterfly fed on while in its larval stages is believed to be one reason for the extinction of the Xerces blue. The plant could not survive in the disturbed soils due to human development, and was no longer available to the Xerces blue. Lupin, Xerces blue's other vegetative food source, was not suitable for the larval stages.
Efforts are on to reestablish related butterflies in the Xerces blue's former habitat. The Palos Verdes blue (Glaucopsyche lygdamus palosverdesensis), which is considered a Los Angeles cousin of the Xerces, is being reared in labs. A new Xerces-like subspecies of the silvery blue (Glaucopsyche lygdamus), which the Xerces blue was thought to be a subspecies of has been discovered as well, and is being analyzed as a potential way to revive the Xerces blue.
In October & December 2021, two entomologists from Jabalpur, India, believed they spotted surviving examples of Xerces blue in Madhya Pradesh. The entomologists collected samples and compared them against images of specimens preserved at the Florida Museum of Natural History. There have been no further reports of surviving examples.
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- Grewe, Felix; Kronforst, Marcus R.; Pierce, Naomi E.; Moreau, Corrie S. (2021). "Museum genomics reveals the Xerces blue butterfly ( Glaucopsyche xerces ) was a distinct species driven to extinction". Biology Letters. 17 (7). doi:10.1098/rsbl.2021.0123. PMC 8292013. PMID 34283930. S2CID 236144945.
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- "Butterfly species thought to be extinct found in Madhya Pradesh". The New Indian Express. 13 January 2022. Retrieved August 25, 2023.