The Life of a Pest tracks the work practices of scientists in Mexico as they study flora and fauna at scales ranging from microscopic to ecosystemic. Amid concerns about climate change, infectious disease outbreaks, and biotechnology, scientists in Mexico have expanded the focus of biopolitics and biosecurity, looking beyond threats to human life to include threats to the animal, plant, and microbial worlds. Emily Wanderer outlines how concerns about biosecurity are leading scientists to identify populations and life-forms either as worthy of saving or as “pests” in need of elimination. Moving from high security labs where scientists study infectious diseases, to offices where ecologists regulate the use of genetically modified organisms, to remote islands where conservationists eradicate invasive species, Wanderer explores how scientific research informs, and is informed by, concepts of nation.