We can learn a lot from our fishing bait. Michigan rivers are home to North America's largest mayfly, the Hexagenia Limbata. Throughout their lives, the hex as anglers call them, take on different forms. After they hatch, they live in the silty bottoms as nymphs or larvae and are mighty creepy looking. Check out these pictures.
Just like a butterfly, the larva forms a chrysalis and and is called a pupa. The pupa transforms and hatches as an adult. This is when the fish go nuts! As the hatching insects are trying to swim to the surface, hungry fish gobble them up. Before the mayflies can fly away, they have to dry their wings while floating on top of the stream. This makes them another easy target. Some actually escape. Look at these images of adult mayflies.
Clever anglers use many baits and lures that look just like the larvae and adults. Sometime when you are fly fishing during this hatch, you'll find out that a fly that simulates the bugs swimming to the surface works better than ones that float on top like a grownup. Some bait stores even sell live larvae. These work great for fish that dig around the dirt and munch on the critters.
Adult mayflies that escape the stream fly upstream and find mates. The females fly back down to the water and lay eggs. Often they die and float downstream to get munched by more fish. The eggs drop to the bottom and the whole cycle starts again.
Remember! When you use Google images, look only at the pictures I have linked. Do not perform searches on your own for other pictures.