Bees are major pollinators of flowering plants, including our crops, orchards and gardens. Without bees, nearly 35% of global crop production would be in jeopardy, thus leading to disastrous consequences for humanity. The massive decline of these insects is a fact accepted by all. Scientists worldwide are currently examining the extent of this decline as well as investigating its causes and consequences. STEP (Status and Trends of European Pollinators), funded by the European Union within its Seventh Framework Programme (FP7), was launched in 2001 to better understand what is affecting bees in continental Europe. The project involves the efforts of more than 20 research centres and universities, including UMONS. Our university is responsible for mapping the diversity of bees and for drawing up a Red List of particularly endangered species.