"It's interesting to reaffirm that what people have been thinking for nearly 100 years is true, that this was a species driven to extinction by human activities," says Felix Grewe, co-director of the Field's Grainger Bioinformatics Center and the lead author of the Biology Letters paper on the project.

"There was a long standing question as to whether the Xerces blue butterfly was truly a distinct species or just a population of a very widespread species called the silvery blue that's found across the entire west coast of North America," says Corrie Moreau, director of the Cornell University Insect Collections, who began work on the study as a researcher at Chicago's Field Museum. "The widespread silvery blue species has a lot of the same traits. But we have multiple specimens in the Field Museum's collections, and we have the Pritzker DNA lab and the Grainger Bioinformatics Center that has the capacity to sequence and analyze lots of DNA, so we decided to see if we could finally solve this question."

To see if the Xerces blue really was its own separate species, Moreau and her colleagues turned to pinned butterfly specimens stored in drawers in the Field's insect collections. Using forceps, she pinched off a tiny piece of the abdomen of a butterfly collected in 1928. "It was nerve-wracking, because you want to protect as much of it as you can," she recalls. "Taking the first steps and pulling off part of the abdomen was very stressful, but it was also kind of exhilarating to know that we might be able to address a question that has been unanswered for almost 100 years that can't be answered any other way."