Mayfly marvels: much more than fish food

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All photos: David A. Brown

You have to believe that a male mayfly has the best pickup lines of any living creature. I mean, the dude has, like, a day — two max — to “round the bases,” so to speak, and it’s not like, “Oh, well, there’s always next weekend.”

Humor aside, the insect synonymous with — but not restricted to — the year’s fifth month, defines purpose and epitomizes determination. When you consider how much mayflies accomplish in a brief period and how much mayflies impact the fishing scene — more on that later — it’s truly a remarkable tale worth exploring.

The profile

Mayflies belong to the order Ephemeroptera and are part of the ancient insect group Palaeoptera, also containing dragonflies and damselflies. The taxonomy traces back to the Greek word “ephemera,” meaning short-lived, and “ptera,” referring to wings — appropriate, given the forthcoming life-cycle description.

According to the University of Florida’s Entomology and Nematology Department, mayflies have inhabited the earth for 300 million years. And talk about diversity: Purdue University’s Mayfly Central tells us that North America claims 658 of the world’s 3,­000-plus mayfly species.

Hexagenia limbata, aka the giant burrowing mayfly, is the most widely distributed North American version. With bodies sharply bowed at both ends, the darker males are typically about an inch long, not including their tail filaments and extending front legs. Lighter colored females follow the same form but can push the inch and a half mark. Both sexes sport the double upturned wings — larger set forward, smaller set rear — common to most mayfly species.

Throughout the mayfly’s coast-to-coast distribution, the majority of species follow a most interesting life cycle concluding in a brief, but remarkably efficient, final act. Here’s how they roll.

The process

After hatching, mayfly nymphs live a year or more underwater, where they cling to rocks or burrow into mud/silt before rising to the surface and molting into the first of two adult stages called the subimago. This stage includes wings, so emerging mayflies can leave the surface, but they’re unable to mate until a second molting reveals the fully formed imago stage.

A couple of interesting anatomical points: Ideally designed for their bottom-hugging lifestyle, mayfly nymphs have flattened bodies with leafy gills along the sides of their abdomens. Also, while omnivorous nymphs sport chewing mouthparts for munching on algae, underwater plants, debris and tiny aquatic animals, adults lack functional mouths. Makes sense — who has time to eat?