Why Were There So Many Fireflies This Year?

Some students have noticed and wondered why there were so many fireflies this year. To answer their questions, the Gazette went to Julie Hagelin, Assistant Professor of Biology who conducts research on animal behavior, and she referred us to Sara Lewis, a Professor of Biology at Tufts University who studies fireflies.

Professor Lewis explained that fireflies spend between one to two years underground as larvae, feeding mainly on earthworms. “A major source of larval mortality would be drought occurring in the fall or spring, so adult firefly populations may have benefited from the wet spring and summer we had this past year,” she wrote in an e-mail. So, the rainy weather of earlier this year is a likely factor in the firefly population boom that was witnessed and appreciated all over Swarthmore’s campus.

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