July 11, 2008

Warm Weather Brings Out Mayflies

By Chris Hubbuch, La Crosse Tribune, Wis.

Jul. 11--La Crosse sidewalks had an extra crunch Thursday after the summer's first big mayfly hatch the night before.

The National Weather Service in La Crosse captured the hatch on radar about 9:45 p.m. Wednesday as millions of the insects emerged from their underwater burrows. The Hexagenia flies native to this area spend most of their lives as larvae under the Mississippi River, rise to the surface when the water temperature is warm enough -- usually in early July. Once they hatch, the insects live only about a day, flying upstream to lay their eggs before dying.

Cal Fremling, a retired biology professor from Winona, Minn., who has studied mayflies for more than 40 years, said this year's hatch is a little later than normal. There will likely be a second hatch later this month.

The flies that end up in La Crosse come from the Brownsville and Stoddard area, Fremling said. That part of the river is good habitat, unlike Pool 6 above Trempealeau, which has filled in with sand.

Mayflies are generally an indicator of a healthy river and are an important source of food for fish and fowl.

"Everybody eats Hexagenia mayflies," Fremling said.

Well, not quite everybody.

Steve Harm, owner of The Warehouse, hosed off the sidewalks outside the music club at Fourth and Pearl streets Thursday morning.

"It's certainly not something you want to be walking on," he said.

Chris Hubbuch can be reached at (608) 791-8217 or [email protected]


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