Tuesday, May 8, 2012

Mayflies: Excerpted from The Dynamic Great Lakes

Mayflies Are Indicators of a Healthy Environment
Around the islands of Lake Michigan and Lake Huron, mayflies are good indicators of a healthy

habitat. Some people call them fish flies;

there are several varieties well known by fishermen who tie artificial


On a warm day in late June or early July, the northern waters of

the Lakes Huron and Michigan and all of Lake Superior undulate

gently. Reflections of trees shine in their glassy waters. Suddenly the

surface pops with the emerging of billions of fish flies wiggling free

from their cases; they are lucky if they live to fly off before a fish

sucks them out of the water first. If they fly, ducklings, songbirds

and flocks of seagulls gobble them like guests at a festive banquet.

The graceful flies with soft bodies and transparent veined wings

that do survive, find a mate, mate, and then the female lays about

3,000 eggs on the surface of the water. The eggs sink to the bottom,

develop into larvae, or the nymph stage. On the bottom they stay for

one or two years, feeding upon plankton and molting up to 30 times

until it is time for them to emerge as adult insects, popping out of

their casings like popcorn. The life cycles begin again.

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