The end of July brought a night of mayflies to much of western Duluth, as seen in this video shot Sunday night at the Holiday Stationstore on the corner of Grand and Central avenues.

A massive hatch led to swarms of the short-lived insects gathering on buildings, streets, signs and anywhere else they could land on Sunday night - far from the first time that’s happened along the St. Louis River corridor, but a spectacle nonetheless.

The Minnesota Department of Natural Resources reports that mayfly hatches are signs of a healthy ecosystem; the insect, “a cornerstone of the aquatic food web, is a very sensitive creature. Sensitive to chemical pollutants, increases in suspended solids (erosion) and decreased dissolved oxygen (DO) levels.”

They’re an important food source for birds, bats and fish.