Mayflies have been around for more than 300 million years – since far before the dinosaurs existed! Mayflies live underwater in streams for most of their lives (as larvae). They can only live in clean water and good habitat. They eat tiny living plants and tiny pieces of dead plants and animals. Amazingly, mayflies transform into adult insects that are able to fly! Adult mayflies have to pairs of transparent wings. The name of the insect (mayfly) is named that since they come out during may. Mayflies can only survive in clean water environments. They cannot live in pollution. The presence or absence of Mayfly larvae is an important indicator of water pollution.