Fish fly swarms have arrived in metro Detroit: When they'll go away
Fish fly season has begun, bringing thousands, if not millions, of the winged insects to swarm the backyards, screen doors and car windows of metro Detroiters.
Fish flies are considered by many to be a messy inconvenience, although the bugs' sensitivity to environmental conditions has led many researchers to use the species and the size of their swarms as an indicator of nearby freshwater ecosystems' health.
And if you still just can't stand the infestation, know that the swarms should end within 10 days of its beginning thanks to their short life cycle.
What are fish flies?
Fish flies, otherwise known as mayflies, are insects with slender bodies, prominent wings, and long antennae and tails.
Fish flies live a mostly aquatic life, hatching from eggs resting in freshwater sediments to feed on algae and other organic matter in their nymph stages of life. They emerge from the water as adults in early summer when water temperatures reach about 68 degrees to reproduce and lay eggs in the water before dying within a day or two of emerging.
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How long do fish flies live?
Within 48 hours a fishfly develops wings, flies toward land, mates and dies, according to MSU Extension. The insect spends 99% of its life in the water.
Unfortunately, carcasses can pile up and smell like rotting fish.
A single fish fly can lay 500 to 8,000 eggs on the water surface.
The fish fly season typically starts in June and can last through August. Scientists aren't sure why they're present for so long, but think it has to do with the timing of different cohorts emerging.
"One cohort has gone through several growth stages and is almost ready to emerge in late summer or fall but is prevented by the declining temperatures," according to MSU Extension. "These are the first cohorts to emerge the following summer. Individuals in the second cohort are smaller in the fall and are not ready to emerge until later in the following summer. There are also two similar but separate species of mayflies in Lake Erie and they may develop at slightly different rates."
Where are fish flies swarming?
While fish flies can be spotted across our lovely Great Lakes State, filled with prime egg-laying space across 11,000 inland lakes, in metro Detroit, the winged insects pop up more in waterfront communities near Lake Erie, Lake St. Clair and the Detroit River.
Are fish flies harmful?
Besides the nuisance of throngs of bugs — as well as the look and smell of their piled bodies as they die — fish flies don't pose a threat to humans or plants. In adulthood, fish flies don't even have mouths to feed from plants.
Why do fish flies exist?
Fish flies act as a plentiful food source for other animals, like birds and bats, while also serving as an indicator of good water quality.
Fish flies live best in clean water with a high oxygen content, so many scientists and researchers view big fish fly hoards as a sign of good water.
During the mid-20th century, fish fly populations were nowhere near the number that we see now; scientists take the larger populations today as living proof of improved water quality in Lake Erie and other waters.
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How do you prevent fish fly swarms?
If you want to stave off a fish fly swarm, you can do so by turning off your lights at night. Like other winged insects, fish flies are attracted to light, so if you remove light sources, they'll be less inclined to flutter around and flit to your property.
This article originally appeared on Detroit Free Press: Fish flies in Michigan: How long mayflies live, their purpose, more
