“By the time he was eight, Fred Urquhart was a bug man.” Though Urquhart’s work has been well documented for young audiences, most recently in Meeg Pincus’ Winged Wonders (2020, illustrated by Yas Imamura), this brisk and lively account of his decadeslong search focuses on the role played by thousands of “amateur scientists,” particularly schoolchildren, of three countries in finally tracking the butterflies to their winter quarters in mountains west of Mexico City. Rosenstock fills in details about the monarch’s life cycle over several appendixes, noting both the worrisome fact that migratory populations have declined in numbers some 80% over the past 20 years and that we still don’t know just how the insects find their way over such a distance. Along with butterfly-strewn representations of Urquhart and his wife, Norah, both White, and groups of volunteers that are diverse in both race and age, Meza, who was born in Michoacán, Mexico, where the monarchs have special significance, especially to the Purépecha and Mazahua people, adds an afterword in which she describes visiting Michoacán and meeting the community that is collectively caring for butterflies through sanctuaries. (This book was reviewed digitally.)