How do you find a ‘lost’ species?

August 14, 2026

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5 min read

In 2005, a firefly with a rosy head and black wings was last seen in a Southern California state park. No one knows if it is a glow worm, a daytime species, or something else entirely. It is one of 28 firefly species in the U.S. and Canada currently classified as lost to science—meaning no one can say for sure where they are or if any remain. This episode of Science Friday examines what it means for a species to be lost, how scientists search for them, and why the distinction matters more than a simple extinction label.

What “lost to science” actually means

Dr. Matt Forrester, a biology professor at the University of Nevada Reno and editor in chief of the Journal of Lost Species, explains that a lost species is one that has not been recorded in the wild in the last ten years, is not in captivity or propagation, and has not been declared extinct by the International Union for Conservation of Nature (IUCN). The definition is straightforward but quickly gets messy. Most species on Earth are not being actively monitored, so the lack of a recent sighting often reflects a lack of search effort rather than genuine absence. “If you don’t know where something is, then it’s lost,” Forrester says. The label is designed to motivate action: it signals that a species needs to be looked for, not just filed away as data deficient.

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What you'll learn

1 Timestamped Outline: How do you find a ‘lost’ species?
2 (01:36) **What Does "Lost to Science" Mean?** - Host Kathleen Davis introduces the concept of species that are lost to science, a category more mysterious than endangered or extinct.
3 (03:22) **Why a Journal for Lost Species?** - Forrester explains the need for a dedicated academic journal to track and memorialize species before they vanish.
4 (04:25) **What Lost Species Mean for Ecosystems** - The ecological consequences of species becoming so rare that they disappear from scientific view.
5 (05:12) **The Detective Work of Finding Lost Species** - Forrester describes the old-fashioned, expedition-based methods used to search for missing organisms.
6 (06:01) **Lost vs. Extinct: The Crucial Gray Area** - How scientists distinguish between a species that is truly extinct and one that is merely lost.
7 (07:30) **A Butterfly That Motivated the Journal** - Forrester shares the personal story of the Sacramento Mountains checkerspot butterfly that inspired the *Journal of Lost Species*.

+ Full timestamped outline available in the app

Show Notes

The earth is facing a biodiversity crisis, and there’s a lot of attention on species that are threatened, or at risk of dying out completely. But, there’s another critter category that’s a little more mysterious: species that are “lost to science.” This means scientists aren’t quite sure how many of them there are out there—or if there are any left at all.

Producer Kathleen Davis talks to biologist Matt Forrister, who is so dedicated to finding more information about these lost species that he created a whole scientific journal about them.

Plus, 28 of the 178 firefly species in the United States and Canada are currently lost to science, according to the community science project Firefly Atlas. We’re joined by firefly researcher Candace Fallon, who is working to confirm which firefly butts are still blinking and which have burnt out.

Want to help find fireflies near you? Find out how to participate in the Firefly Atlas.

Guests:

Dr. Matt Foristor is a professor of biology at the University of Nevada-Reno and editor-in-chief of the Journal of Lost Species.

Candace Fallon is a senior endangered species conservation biologist at the Xerces Society for Invertebrate Conservation.

Transcripts for each segment will be available the week after the show airs on sciencefriday.com.

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