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Sex-crazed mayflies blanket Downtown
Friday, June 08, 2001 By Don Hopey, Post-Gazette Staff Writer
Workers in Downtown office buildings near the Allegheny River were greeted yesterday morning by thousands and thousands of big, wispy-winged mayflies, a common sight along your better trout streams but a rarity over the last 150 years in Pittsburgh.
That these aquatic insects have reappeared in this urban, once highly industrial city is a visible indication that water quality in the rivers is improving.
"It's great that they've emerged this year," said April Moore, an aquatic biologist with the state Department of Environmental Protection. "If they create a stir it's because they're unfamiliar. On the upper reaches of the river they are common."
The mayflies, which measure about 2 inches from their heads to the tips of their two hair-like tails and have triangular, sail-like wings that stand out from their thin bodies, hatched in the Allegheny River, probably Wednesday evening, and were seen swarming along Penn and Liberty avenues yesterday morning.
They could later be found clinging in great numbers to the walls of the Clark and Dimling buildings, both on Liberty Avenue, and on the Benedum Center on Seventh Street and Penn Avenue.
On Dominion Tower, also on Liberty, mayflies could be seen on most of the windows all the way up to the 32nd floor and initially prompted excited calls to the building manager about swarms of locusts.
"When I came in at 9:15 this morning there was already a flurry of activity in the office and people were calling the building manager about bringing in an exterminator," said Caren Glotfelty, director of the environmental program for the Heinz Endowments on the Dominion Tower's 30th floor.
"I identified them as mayflies and made sure to call off the exterminators. People were crunching across the dead carcasses of these critters on the way to work and so many people are so bug-adverse, but mayflies are really a cause for celebration because they're an indicator that the river is getting cleaner."
Mayflies have been around in one form or another for 350 million years and remain a fairly primitive grouping of insects that is extremely sensitive to pollution.
The insects hatch from eggs in river, creek or lake bottom sediment, where they then spend up to two years before swimming to the surface and flying to shore, usually in the evening. On land or some other hard surface, they molt, then mate in the air before the females fly back over water to deposit as many as 8,000 eggs and die. The eggs sink into the sediment at the lake bottom.
The whole adult process, from the time the mayfly nymph swims to the surface of the body of water and its wings emerge, usually takes only 24 hours, hence the name of their insect order -- Ephemeroptera, from the Greek ephemeros, meaning of a day's duration, and pteron meaning wing.
During that one day, mayflies are mating machines. Some mayfly species are so focused on sex that an immature, sub-adult stage is compressed to as little as five minutes. Others become adults without mouths or digestive systems because with only 24 hours to live, they don't want to waste time eating.
Mayflies emerge sporadically on different days from mid-May through July, depending on species, life cycle and water temperature.
Such "hatches," as they are known to fishermen, are common on Pennsylvania's creeks and rivers where, after mating, they drop spent into the water where they are eaten by trout and other fish.
Emil Svetahor, regional manager for the Pennsylvania Fish and Boat Commission, said such mayfly hatches and spinner falls are common on the Allegheny River around Ford City and Kittanning in Armstrong County, more than 40 river miles from Pittsburgh. He hadn't heard of one in Pittsburgh before.
"They can be quite spectacular and even blanket an area of the river," Svetahor said. "Some people might not like it because the mayflies can be all over the place, but it means the water quality is improving."
The swarming, molting mayflies surprised many people Downtown, but not Meredith Mueger, education specialist on the Pittsburgh Voyager, a ship that docks at the Carnegie Science Center on the North Side and regularly samples water quality and bottom sediment in the rivers as part of its environmental education cruises with grade school, high school and college students.
She said the Voyager's sediment sampling has identified three different species of mayfly larvae, as well as caddis and stone fly larvae.
"I've been working here for three years and we're finding more and more mayfly nymph stages in all three of our rivers.," Mueger said. "Last year we had two different species hatch and cover our boat and dock so heavily that some of our students were afraid to get onboard the boat."
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