It Isn’t a Thunderstorm. It’s Mayflies

Those that live near populations of mayflies are all too familiar with the unbelievably large swarms that appear each summer. Some of these swarms in Wisconsin are even dense enough to show up on weather radar as rainstorms.

Mayflies are unique in that they spend most of their life in water. They only live as mature adults for a few days at most. However, mayflies are a sign of healthy water systems, as they are very sensitive to pollution in rivers and lakes.

When adults emerge from the water, they swarm in huge numbers and are very attracted to lights at night. Swarms have even been blamed for car accidents as the roads are covered in both living and dead insects.