Monarch butterfly populations have declined by over 80% in recent decades due to habitat loss, pesticide use, and climate change, raising questions about insect welfare at scale.
The welfare significance of monarch butterflies depends on philosophical positions about insect sentience and the capacity for suffering in insects with simpler nervous systems than vertebrates. From an individual welfare perspective, monarchs face mortality during migration from exhaustion, predation, and parasitism. Population-scale welfare considerations recognize that massive population decline represents the elimination of billions of individual lives and the disruption of complex ecological relationships. Regardless of individual insect welfare status, monarchs serve as a flagship species whose protection drives conservation of habitats that support vast numbers of other species whose sentience and welfare significance is clearer. Habitat restoration efforts that provide milkweed and nectar resources benefit monarchs and the broader insect community.