Monarch butterfly populations have declined by over 80% in recent decades due to habitat loss, pesticide use, and climate change, raising growing concern about the welfare of billions of individual insects during their extraordinary migration.
Whether insects experience welfare in a morally significant sense remains scientifically debated, but monarchs face conditions that would compromise wellbeing in any sentient creature. Pesticide sublethal exposure impairs flight and navigation, leading to failed migration and starvation. Habitat fragmentation means monarchs cannot find adequate nectar or milkweed during critical life stages. For those who consider insect sentience possible, the scale of population decline represents a massive welfare concern affecting billions of individuals annually.