Hidden in Mother Nature's algorithm for creating life are the instructions for the Ephemeroptera, the Mayflies. An ancient order of insects whose adult lives are short - fantastically short compared to the years that the nymph stage can live. In fact, the adults of some species emerge from their aquatic forms, rise from the surface of a lake or stream into the air, mate, lay their eggs, and expire in only a few minutes. Their ephemeral lives have been romanticized in literature for centuries - most often as a metaphor proving that life is short. I learned about mayflies when I heard about their sudden hatches from clear streams in the mountains and the country north of where I grew up and I have long admired their beauty.
In my training as a naturalist, I came to value the mayflies for a different reason. The mayflies are considered indicator species and their absence or presence tells us something about the ecosystem in which they live. That's because mayflies do not tolerate pollution, or low water quality, or unnatural swings in water conditions. In addition, because the immature forms live for a long time, their disappearance may provide evidence of ecological pollution long after the event has been swept downstream. Finally, mayflies typically form part of a diverse community of organisms in a healthy ecosystem. That diversity can be measured and summarized as an index and the health of different aquatic ecosystems can be rated by comparing their index of heterogeneity - a task that can be performed without the necessity of being able to key organisms to species level. It is only necessary to be able to tell different organisms apart from each other, which can be done without years of training and study.
Understanding the life cycle of the mayflies not only helps us appreciate the marvelous and fleeting beauty of our natural world, but also helps us understand our place in this world. And because we and mayflies both depend on the health of our environment, when the existence of the mayflies are threatened we can be sure that our existence is threatened for the same reasons.