"Bees pollinate 75 percent of the fruits, vegetables, and nuts grown in the United States. Around the world, bees pollinate $24 billion worth of crops each year. Without bees, humans would face a drastically reduced diet. We need bees to grow the foods that keep us healthy. But numbers of bees are falling, and that has scientists alarmed. What's causing the decline? Diseases, pesticides, climate change, and loss of habitat are all threatening bee...