Monarch butterfly populations have declined by over 80% in recent decades due to habitat loss and pesticide use — raising questions about insect welfare at scale that deserve serious consideration.
The welfare of insects remains scientifically uncertain, but the precautionary principle and the sheer scale of insect populations makes this a morally important question. Monarchs specifically face starvation risk during migration when nectaring opportunities are reduced; sub-lethal pesticide exposure causes disorientation and navigation failure that can translate into prolonged suffering and death far from overwintering sites. The population collapse represents the loss of trillions of individual lives over decades. Even setting aside individual insect sentience, the ecological cascade from pollinator decline — including effects on the plant and vertebrate communities that depend on them — creates compounding welfare impacts across the food web. Supporting milkweed planting and pesticide reduction addresses both individual monarch welfare and broader ecosystem health.