How to Handle the Fish Fly Invasion: A Brief Guide for Metro Detroit Residents

As temperatures soar in metro Detroit, the skies are filled with swarms of fish flies, also known as mayflies, invading backyards, screen doors, and car windows. While these winged insects might seem like a messy inconvenience, their presence actually signals the health of nearby freshwater ecosystems.

Understanding Fish Flies

Fish flies, or mayflies, are characterized by their slender bodies, prominent wings, and long antennae and tails. They spend most of their lives in water, hatching from eggs in freshwater sediments to feed on algae and organic matter. Once they emerge as adults in early summer, they reproduce and die within a span of just 48 hours.

Swarming Locations

While fish flies can be found across Michigan, they tend to swarm more densely in waterfront areas near Lake Erie, Lake St. Clair, and the Detroit River. These locations provide ideal conditions for egg-laying and reproduction.

Harmlessness of Fish Flies

Despite their overwhelming presence and the inconvenience of their remains, fish flies pose no threat to humans or plants. They serve as a crucial food source for birds, bats, and other wildlife, indicating the health of freshwater ecosystems.

The Role of Fish Flies

Fish flies are vital to ecosystem health, thriving in clean water with ample oxygen levels. Their increased population in recent years is a positive sign of improved water quality in bodies of water like Lake Erie.

Preventing Swarms

To reduce fish fly swarms around your property, consider turning off outdoor lights at night. Like many winged insects, fish flies are attracted to light sources, so minimizing illumination can help deter them from gathering in large numbers.

While fish fly swarms may disrupt outdoor activities temporarily, their presence underscores the delicate balance of nature and the well-being of freshwater ecosystems in metro Detroit. As their swarms naturally dissipate within about 10 days, residents can appreciate their contribution to sustaining the natural world around them.

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