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Mayflies

Scientific Name
MatchScientific Name
****Ephemeroptera

Mayflies are the most important insects for anglers to understand, because they are common on trout streams, they often hatch in frenzied bursts of activity, and their behavior varies so widely between families and sometimes even species that it's useful to know and imitate the habits of each. They are a primitive order of insects, and their elegance and delicate lives have made them popular beyond the world of trout fishing.


This common name refers to only one order.

Insect Order Ephemeroptera

These are pretty much always called Mayflies.
Mayflies may be the most important insects for trout anglers to understand. They are an ancient order of insects, famous outside the fly-fishing world for their fragile beauty and short adult lifespan, often a single day to mate and die. The mayfly's poignant drama attracts poets and anglers alike, but anglers make the most of it.

Mayflies live more than 99% of their lives as nymphs on the river or lake bottom, filling many crucial roles in freshwater ecosystems as they feed and grow. They eventually emerge from the water as winged sub-adults called "subimagos" by scientists and "duns" by anglers. Duns evolved to be good at escaping the water, with a hydrophobic surface and hardy build, but they are clumsy fliers. Within a day or two they molt one last time into "imagos" or "spinners," the mature adults, a transformation captured in this photo series of a dun molting into a spinner. They have longer legs and tails, and sleeker, more lightweight bodies, giving them the airborne speed, agility, and long grasp they need for their midair mating rituals. They are usually darker than the duns and have shinier, more transparent wings. They die within minutes or hours after mating.
Baetisca obesa (Armored Mayfly) Mayfly NymphBaetisca obesa (Armored Mayfly) Mayfly Nymph View 12 Pictures
Collected May 6, 2007 from in
Added to Troutnut.com by on May 10, 2007
Drunella pelosa Mayfly LarvaDrunella pelosa  Mayfly Larva View 1 PicturesThis is a common species in states like Oregon and Washington but this is only the second time it has been collected in Montana.
Collected June 20, 2007 from in
Added to Troutnut.com by on June 26, 2011
Male Baetis (Blue-Winged Olives) Mayfly DunMale Baetis (Blue-Winged Olives) Mayfly Dun View 14 PicturesThis dun molted most of the way into a spinner (though the wings got stuck) the evening after I photographed it, so I took some more photos of the spinner.

I found a female nearby, probably of the same species.
Collected September 19, 2006 from in
Added to Troutnut.com by on October 4, 2006
Male Isonychia bicolor (Mahogany Dun) Mayfly SpinnerMale Isonychia bicolor (Mahogany Dun) Mayfly Spinner View 15 PicturesI got several really nice pictures of this spinner. I also collected a female on the same trip.
Collected August 9, 2006 from in
Added to Troutnut.com by on August 11, 2006
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