DNA Confirms First US Case of Insect Extinction Caused by Humans A butterfly specimen collected 93 years ago gave researchers the DNA to prove it was a distinct species and the first American insect wiped out by urban development. A 93-year-old Xerces blue butterfly specimen. (Credit: Field Museum) (CN) — The Xerces blue butterfly was last seen in the early 1940s in San Francisco. The small, iridescent blue insect, originally discovered in 1852, was endemic to and once plentiful among the coastal sand dunes of the upper San Francisco Peninsula, then abruptly disappeared amid habitat loss caused by urban development. Though the Xerces blue is typically recognized as the first American insect species destroyed by urban development, questions persisted over whether it was really its own species to begin with or simply a subpopulation of another common butterfly.