Troutnut.com Fly Fishing for Trout Home
User Password
or register.
Scientific name search:

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 Ephemerella aurivillii Mayfly DunMale Ephemerella aurivillii  Mayfly Dun View 14 PicturesThis is the most widespread species of Ephemerella, and also the most abundant in some places, but nobody I've talked to seemed to know what its duns looked like, and there were no pictures of its duns online or in any angling books. That mystery is solved with this male dun, which hatched from a definitively identified nymph.
Collected July 10, 2011 from in
Added to Troutnut.com by on July 12, 2011
Male Ephemerella aurivillii Mayfly SpinnerMale Ephemerella aurivillii  Mayfly Spinner View 15 PicturesThis spinner molted from a dun after being photographed, and the dun form is listed here as a separate specimen. I've rarely found a more cooperative and photogenic mayfly.
Collected July 10, 2011 from in
Added to Troutnut.com by on July 16, 2011
Top 10 Fly Hatches
Top Gift Shop Designs
Top Insect Specimens
Miscellaneous Sites