According to the Nature Conservancy, there are more than 1100 species of bats around the world, and they make up more than a quarter of the worldwide mammal population. They range in size from the itty bitty 2-gram bumble bee bat, to the hefty, 1.5-kg "flying fox." They are very important for pest control as each one can eat more than 1000 mosquitoes in an hour. They're also an important pollinator; just like bees, some species feed on nectar or fruit, and they help spread pollen from plant to plant. Only three species are the so-called "vampire" variety, and none of them live in the US. And although we don't like to think about it, bat droppings, also known as guano, are a rich fertilizer, and it was once a major trade item.