Bees and other pollinators, such as butterflies, bats and hummingbirds, are increasingly under threat from human activities. Pollinators allow many plants, including many food crops, to reproduce. Not only do pollinators contribute directly to food security, but they are key to conserving biodiversity – a cornerstone of the Sustainable Development Goals. They also serve as sentinels for emergent environmental risks, signaling the health of local ecosystems. To raise awareness of the importance of pollinators, the threats they face and their contribution to sustainable development, the UN designated 20 May as World Bee Day.