Mayflies begin annual invasion

MARBLEHEAD Just when you thought the mufflehead invasion was tapering, a new plague of winged pests
Sarah Weber
May 24, 2010



Just when you thought the mufflehead invasion was tapering, a new plague of winged pests has besieged the area.

The first hatch of mayflies landed this week in thick swarms in Marblehead, Port Clinton and other shoreline and island communities.

Marblehead and Port Clinton officials have preemptively tried to stem the siege by darkening the city street lights.

This years-old practice reduces attraction of the pesky insects as they emerge from their nymph phase in the muddy bottom ofLake Erie.

Larger than the muffleheads, which look like oversized mosquitos, the mayflies' long bodies and large wings cause a considerable mess, piling up under lights and sticking to buildings and sidewalks.

Ken Krieger, a mayfly expert and senior researcher at Heidelberg University, said reducing light in the communities has been proven to diminish the number of winged visitors.

The number of mayflies that swarm to local shores, however, has in large part to do with the strength and direction of the wind.

"People need to realize they are mainly just a nuisance," Krieger said. "They really don't bite, they don't have stingers, they don't really cause any harm. The few weeks of nuisance are compensated for by the valuable food source mayflies are to local fisheries."

He said the mayfly nymphs are a favorite food of yellow perch. Fisherman report finding mayfly nymphs in the stomachs of yellow perch even during the winter, Krieger said.

The large winged insects usually emerge in droves in mid-June. Stragglers arrive through the summer and as late as early fall.

The mayfly eggs usually hatch a week to 10 days after they are laid in mud beds in the lake. They live as nymphs in the mud for a year until they emerge from the lake as sub-adults the following June.

Once they reach land, they molt, becoming full-fledged adults. That night, they gather in a mating swarm around dusk and procreate the next generation of mayflies.

Then they die, leaving millions of smelly, slippery carcasses everywhere -- on windows, decks and city streets. The bugs only live for 24 to 36 hours after they emerge from the water, Krieger said.

In Port Clinton this week, city workers had to wear bug netting to ward off mayflies while mowing grass and working outside.

Marblehead mayor Jackie Bird said the bugs were thick in the village last weekend. She heard the familiar sound of dead mayflies under her tires as she pulled out of her driveway.

"Going up my street was 'crunch'," she said. "They are just a general nuisance."