American Scientist

SILENT SPARKS: The Wondrous World of Fireflies. Sara Lewis. xiv + 223 pp. Princeton University Press, 2016. $29.95.

Call these creatures what you will—lightning bugs, glowworms, fireflies—but watching an evening go by, the air lit by their sparks, is one of summertime’s simple pleasures. Development of the characteristics that happen to make fireflies so recognizable and charismatic has, however, involved complex processes. Over millennia, fireflies have followed widely varied evolutionary paths. In fact, nearly 2,000 species of fireflies have been discovered globally.

This level of complexity might present a serious narrative challenge for some, but Tufts University biologist Sara Lewis’s fascination with these insects is captivating and infectious. From Japan to New England, Appalachia to Malaysia, Lewis explores how fireflies have specialized, occasionally to the point that their ostensibly defining features, “fire” and flight, have vanished. Some species require very specific habitats, such as Japan’s Genji firefly (below), which relies on rivers and streams, living underwater during the larval stage. Lewis talks to researchers who specialize in studying firefly species, considers threats to their habitats, and discusses the firefly as it has appeared in art and literature. She also supplies a handy field guide to the five most common groups of North American fireflies. Helpful notes direct readers to resources that will reveal more about finding, identifying, and understanding their own local species.