Most people think of moths flying at night—but some, including the one pictured here, are active in the daytime. In arid, sandy areas of California and Baja Mexico, Euproserpinus phaeton moths take wing on early spring days. They fly rapidly, just inches from the ground, often in search of mates or evening primrose flowers, for nectar and on which their caterpillars later feed.

But in populated areas in California, the moths’ range seems to be shrinking: entomologists no longer see them in places they used to thrive, where people have built new homes over open land. Meanwhile, a very closely related moth,: Euproserpinus euterpe, is found in just two small areas in rural central California. For that imperiled species, even a minor disruption to its tiny habitat could be enough to spell doom.