Mayfly lay their eggs in water. The babies (larvae) may live in streams for 2-3 years. They breath with gills on their sides that they wave in the water to get oxygen.
They usually feed on microscopic plants and little bits of debris.
Adult mayflies may only live for 24 hours as an adult! They have to find a partner, mate and lay eggs all in a day. Many mayflies don’t even have time to eat.
Many mayflies are very sensitive to polluted water.