Early one morning during the last week of June, I noticed several adult green-tinted, big-winged Mayflies with long tails sitting on several tall pieces of shoreline vegetation and the dock. They had just "hatched" after spending most of their lives as nymphs in the lake for the past year. I cheered! I recalled what I had learned about invertebrate through the Minnaqua educational program related to the Governor's Fishing Opener 2013 here in Park Rapids. The presence of Mayflies, a cornerstone of the aquatic food web, meant the lake had adequate oxygen levels and wasn't suffering from too much erosion nor chemical pollutants! The Mayfly is sensitive - sort of like the canary in the gold mine.
A couple days later, I noticed that there wasn't a Mayfly to be seen on the shore except two that had perished in the cobwebs in a boat; their color now gone. Where did the Mayflies go? I checked the Minnaqua website to refresh my memory and was re-inspired about their cycle of life and the food chain interactions that take place in and near our area lakes and rivers.
Afteremerging from the water, it takes a few days to become a mature adult with a lifespan of up to a month. Adult Mayflies are eaten by birds and bats. Perhaps sometime in July, if I pay really close attention in the evening, I will be fortunate enough to observe a mating flight from the water's edge. According to the Minnaqua information, a female Mayfly flies through a swarm of males during mating. She then returns to the water to lay her eggs and dies. The cycle of life begins anew. The egg stage lasts two weeks and then the Mayfly nymph stage begins again. The fish and other invertebrate like Crayfish search out and eat the Mayfly nymph. The Common Loon, the Bald Eagle, the Osprey and the Great Blue Heron are all sustained through this food chain!
The lakes, rivers and streams of our area provide the aquatic habitat which supports many invertebrate that spend a good deal of their own life cycle in the healthy waters. Species have different and unique life stages when compared to that of the Mayfly. The wide variety of colorful dragonflies and damselflies that we enjoy during the summer have a nymph stage too. Sometimes, the nymph of the dragonfly can spend more than one year in that stage of life. Many Caddisfly create a case of rocks or sticks as part of their life cycle. As you spend time at the water's edge this summer, take a small minnow net and gently scoop water and debris in the water near the shoreline rocks and logs and put it in a white dishpan to "see" what you find. Use the online Minnaqua resources to learn more about the macroinvertebrate you discover. You may develop a new appreciation for the insect's life cycles supported by the area lakes and rivers!