The United Nations declared 20 May to become World Bee Day. Bees and other pollinators are vital to the global food chain. In fact, the bee is considered the third most important livestock of humans (after cattle and pigs). They provide an economic service worth up to $500bn, according to the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES). The insects are a key part of many ecosystems and therefore a good indicator of ecosystem health. Pollinators have declined by up to three-quarters in Europe over the last 30 years. While the exact cause is unclear, many scientists point to the rise in neonicotinoid pesticides as a major contributing factor.