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1. female mayflies usually live up to five minutes after larvae stage while males can live up tp two days.

2. mayflies live most of their lives underwater.

3. mayflies have been around for more than 300 million years.

4. At the end of the mayfly life cycle, after mating, the females fall to the water and lay their eggs. Then both male and female mayfly act as food for hungry fish and birds.

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Mayflies have an incomplete metamorphosis but it is a bit of a unique version of hemimetabolism.The life cycle of mayflies consists of four stages: egg, nymph, subimago, and imago.

egg stage: They begin as a fertilized egg laid by female mayflies in the water, which develops into a nymph or more technically a naiad. mayfly eggs could take ten days to several months to hatch.

Nymph stage: Nymphs go through a number of molts (ecdysis) as they grow and get larger.Nymphs are generally broken into four categories based on where and how they live and feed as nymphs - swimmers, clingers, crawlers, and burrowers.

adulthood: In transitioning to adulthood, nymphs emerge to become "duns" basically a "pre-adult" stage. This happens in different places and different rates of speed for different species. Mayflies then undergo one more metamorphosis to become imagos or spinners.

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Updated: Feb 27, 2023

Before we get into each order, there is a bit of terminology about life histories shared by some of these orders. These insects all undergo metamorphosis but mayflies and stoneflies undergo an incomplete metamorphosis ( hemimetabolism ) and have egg, nymph, and imago or adult stages. Whereas caddis and midges undergo complete metamorphosis ( holometabolism ) which involves a pupal stage before the imago (adult) stage. Understanding these stages, how insects transition from one to the next, and for different hatches, which stages or transitions are most important, I think is an important step in any fly angler's learning process.

Swimmers - well, they swim, so they mostly - but not always - live in slower currents and are often associated with vegetation. The best known of these are ( slate drakes ), ( Blue-winged Olives or BWOs ), and ( speckled spinners ) which are best known from lakes.

Clingers - again, the name sort of gives it away; these nymphs are dorso-ventrally flattened and the "cling" to rocks. They tend to be wide but from top to bottom, very thin. They can live in the fastest of currents. These are largely - but not entirely - in the family Heptageniidae . The species you maybe familiar with are the March browns, both eastern and western , light Cahills , and quill Gordons .

Crawlers - These are many of our early or mid- season hatches - the sulphurs ( and, in places, some other species), Hendrickson ( ), Tricos - those small "white-winged black curse" mayflies ( spp.), and pale evening and pale morning duns ( Ephemeralla spp.). Crawlers are mostly riffle-dwellers but maybe not in the very fastest of water that is home to clinger nymphs. Some crawlers are more at home in slower waters of runs and pools.

Burrowers - obviously these make burrows and they are some of our largest mayfly species. To make these burrows, these species need relatively soft, small, and stable substrates which often occur in downstream reaches of our trout streams or in larger trout rivers. These are often our "drakes" a not so scientific name for larger mayflies that include the Hexagenia spp., Eastern Green Drake ( ), and brown drake ( ) along with the white mayflies ( spp.) of late summer.

To simplify this for the angler, nymphs vary a bit in shape but honestly, fishing a clinger or a more flattened crawler imitation probably makes no difference to the fish. After all, perdigons and other nymph imitations that look little like real nymphs work really well. One of the best reason to learn some of the major hatches in your area is that for different species, different stages are more or less susceptible and thus some are better to imitate than others. For example, blue-winged olives often hatch during overcast and rainy times of days and as swimmers, they are likely swim quickly to the surface - look for splashy rises of trout trying to "catch up" to these swimming nymphs. At the surface as they emerge from a nymph to a dun, they make "get stuck" between stages, particularly when air temperatures are low, and this makes them particularly susceptible to trout. For other species, like Tricos, Ephorons , and Hexagenia , spinners are typically the most important stage to imitate. And for the burrowing mayflies, they are generally only available to fish when they are emerging but at his time they can be incredibly important.

Stoneflies are of relatively little importance in Wisconsin. The three ways I have fished stoneflies in Midwest streams are fishing large nymphs through riffles rapids in large northern streams, the yellow sally hatch in June, and the winter stoneflies. Yellow Sallies are a June hatch and run about a size 14 and can be dependable on some streams. The winter stoneflies which tend to be small (#18 to #22 ), dark, and hatch during the warmest part of a winter day can be fun. They are probably not hugely important to the angler but it is always nice to catch a trout on a dry fly in January and February. In general, stoneflies are much more common on freestone streams, particularly in the western US.

Caddis and midges undergo a complete metamorphosis which means that like butterflies ( order Lepidoptera ), they have a pupal stage (egg, larva, pupa, adult). Probably the most interesting thing about caddis are that they have a diversity of different types of larva. While caddis are best known for the diversity of cases that different species make, there are also net-spinning and free-living caddis. In any case, all caddis have simple "worm-like" larva that are identified by their 2 anal hooks. A number of species use the silk that they produce to make a case from sand, pebbles, organic matter, or other materials - each case type is unique to the species. There are a ton of different "peeking" or cased caddis a patterns to imitate cased caddis which occasionally get dislodge - often by trout that will try to eat them off the rocks. Hydropsyche caddis are a common net spinning family of caddis that are abundant in many streams. As adults, these are often the size 14 (or so) tan caddis that typically hatch from mid-May to Mid-June. And the most common free-living caddis you are likely to come across in most places are the caddis or "green rock worms".

For more about caddis entomology; posts from Winona Fly Factory: Parts 1 , 2 , 3 , and the last post .

Last but not least are the midges which are very important hatches, particularly in the winter. Many anglers have a love-hate relationship with midges (maybe its more hate than love). The problem with midges is that they are small which makes them difficult to imitate effectively (and to thread onto a tippet). Probably the best known midge pattern, the - imitates a mating cluster of midges which gets around the issue of them being really small; although Griffith Gnats tend to be tied in Griffith's Gnat #18 and #20 most of the time.

I am going to sneak crane flies in here too as they are related - they are both dipterans (true flies). For more on crane flies, which are mostly but not entirely in the families Limoniidae and Tipulidae , I wrote a post in praise of crane flies .

The Wrap-up

Knowing a bit about the life cycles of the major aquatic insect orders helps make you a better angler. If you do not care to learn a bunch of entomology ( ), carry imitations in a few different sizes, shapes (up-wing and down-wing), and in a few different colors or shades. There is the old adage that you should match - in order - size, shape, and then color. Some anglers put behavior as the first in the list - a post for another day. In any case, you do not need to try to imitate every species because a few general patterns in a few sizes. Most of our Driftless hatches are how much do I need to know? #14 on the large size to #20 on the small side and a #16 or #18 is what I fish most often. No need to make it more complicated than it needs to be - caddis, mayflies, and craneflies are what you're most likely to encounter from about April until the end of the season.

Wisconsin Hatch Charts

Websites for Angling Entomology

YouTube Videos

Before we get into each order, there is a bit of terminology about life histories shared by some of these orders. These insects all undergo metamorphosis but mayflies and stoneflies undergo an incomplete metamorphosis ( hemimetabolism ) and have egg, nymph, and imago or adult stages. Whereas caddis and midges undergo complete metamorphosis ( holometabolism ) which involves a pupal stage before the imago (adult) stage. Understanding these stages, how insects transition from one to the next, and for different hatches, which stages or transitions are most important, I think is an important step in any fly angler's learning process.

Swimmers - well, they swim, so they mostly - but not always - live in slower currents and are often associated with vegetation. The best known of these are ( slate drakes ), ( Blue-winged Olives or BWOs ), and ( speckled spinners ) which are best known from lakes.

Clingers - again, the name sort of gives it away; these nymphs are dorso-ventrally flattened and the "cling" to rocks. They tend to be wide but from top to bottom, very thin. They can live in the fastest of currents. These are largely - but not entirely - in the family Heptageniidae . The species you maybe familiar with are the March browns, both eastern and western , light Cahills , and quill Gordons .

Crawlers - These are many of our early or mid- season hatches - the sulphurs ( and, in places, some other species), Hendrickson ( ), Tricos - those small "white-winged black curse" mayflies ( spp.), and pale evening and pale morning duns ( Ephemeralla spp.). Crawlers are mostly riffle-dwellers but maybe not in the very fastest of water that is home to clinger nymphs. Some crawlers are more at home in slower waters of runs and pools.

Burrowers - obviously these make burrows and they are some of our largest mayfly species. To make these burrows, these species need relatively soft, small, and stable substrates which often occur in downstream reaches of our trout streams or in larger trout rivers. These are often our "drakes" a not so scientific name for larger mayflies that include the Hexagenia spp., Eastern Green Drake ( ), and brown drake ( ) along with the white mayflies ( spp.) of late summer.

To simplify this for the angler, nymphs vary a bit in shape but honestly, fishing a clinger or a more flattened crawler imitation probably makes no difference to the fish. After all, perdigons and other nymph imitations that look little like real nymphs work really well. One of the best reason to learn some of the major hatches in your area is that for different species, different stages are more or less susceptible and thus some are better to imitate than others. For example, blue-winged olives often hatch during overcast and rainy times of days and as swimmers, they are likely swim quickly to the surface - look for splashy rises of trout trying to "catch up" to these swimming nymphs. At the surface as they emerge from a nymph to a dun, they make "get stuck" between stages, particularly when air temperatures are low, and this makes them particularly susceptible to trout. For other species, like Tricos, Ephorons , and Hexagenia , spinners are typically the most important stage to imitate. And for the burrowing mayflies, they are generally only available to fish when they are emerging but at his time they can be incredibly important.

Stoneflies are of relatively little importance in Wisconsin. The three ways I have fished stoneflies in Midwest streams are fishing large nymphs through riffles rapids in large northern streams, the yellow sally hatch in June, and the winter stoneflies. Yellow Sallies are a June hatch and run about a size 14 and can be dependable on some streams. The winter stoneflies which tend to be small (#18 to Pteronarcys #22 ), dark, and hatch during the warmest part of a winter day can be fun. They are probably not hugely important to the angler but it is always nice to catch a trout on a dry fly in January and February. In general, stoneflies are much more common on freestone streams, particularly in the western US.

Caddis and midges undergo a complete metamorphosis which means that like butterflies ( order Lepidoptera ), they have a pupal stage (egg, larva, pupa, adult). Probably the most interesting thing about caddis are that they have a diversity of different types of larva. While caddis are best known for the diversity of cases that different species make, there are also net-spinning and free-living caddis. In any case, all caddis have simple "worm-like" larva that are identified by their 2 anal hooks. A number of species use the silk that they produce to make a case from sand, pebbles, organic matter, or other materials - each case type is unique to the species. There are a ton of different "peeking" or cased caddis a patterns to imitate cased caddis which occasionally get dislodge - often by trout that will try to eat them off the rocks. Hydropsyche caddis are a common net spinning family of caddis that are abundant in many streams. As adults, these are often the size 14 (or so) tan caddis that typically hatch from mid-May to Mid-June. And the most common free-living caddis you are likely to come across in most places are the Rhycaphilia caddis or "green rock worms".

For more about caddis entomology; posts from Winona Fly Factory: Parts 1 , 2 , 3 , and the last post .

Last but not least are the midges which are very important hatches, particularly in the winter. Many anglers have a love-hate relationship with midges (maybe its more hate than love). The problem with midges is that they are small which makes them difficult to imitate effectively (and to thread onto a tippet). Probably the best known midge pattern, the - imitates a mating cluster of midges which gets around the issue of them being really small; although Griffith Gnats tend to be tied in Griffith's Gnat #18 and #20 most of the time.

I am going to sneak crane flies in here too as they are related - they are both dipterans (true flies). For more on crane flies, which are mostly but not entirely in the families Limoniidae and Tipulidae , I wrote a post in praise of crane flies .

The Wrap-up

Knowing a bit about the life cycles of the major aquatic insect orders helps make you a better angler. If you do not care to learn a bunch of entomology ( ), carry imitations in a few different sizes, shapes (up-wing and down-wing), and in a few different colors or shades. There is the old adage that you should match - in order - size, shape, and then color. Some anglers put behavior as the first in the list - a post for another day. In any case, you do not need to try to imitate every species because a few general patterns in a few sizes. Most of our Driftless hatches are how much do I need to know? #14 on the large size to #20 on the small side and a #16 or #18 is what I fish most often. No need to make it more complicated than it needs to be - caddis, mayflies, and craneflies are what you're most likely to encounter from about April until the end of the season.

Wisconsin Hatch Charts

Websites for Angling Entomology

YouTube Videos

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Angling Entomology: Life Cycles (A simplified guide to knowing the "bugs")

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Understanding these stages, how insects transition between them, and for different hatches, which stages or transitions are important is key

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Winged mayflies have large compound eyes, short, bristlelike antennae, and functionless mouthparts and digestive tracts.

Once mayflies enter the winged stages they cannot feed. Their membranous wings include a large, triangular front pair and a much smaller, rounded hind pair.the wings are held together upright over the body like those of a butterfly.

Nymphal characters include a single claw terminating each of the six legs.

The abdominal region is usually long and slender. Gills are attached to the outer edge of the upper surface of some of the ten segments into which the body is divided.

adult mayflies of North American species range in body length,

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Mayfly | Insects, Aquatic Larvae & Metamorphosis | Britannica

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Mayfly, (order Ephemeroptera), any member of a group of insects known for their extremely short life spans and emergence in large numbers in the summer months. Other common names for the winged stages are shadfly, sandfly, dayfly, fishfly, and drake. The aquatic immature stage, called a nymph or

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Food source

Mayflies are a key food source for many animals, including fish, birds, bats, and other invertebrates. Mayfly nymphs are eaten by fish like trout, while mayfly eggs are eaten by caddisfly larvae and snails.

Indicator of water health

Mayflies are sensitive to pollution and are often found in high-quality, minimally polluted bodies of water. They are one of the most common indicators of aquatic ecosystem health.

Habitat

Mayflies provide habitat for other organisms.

Environmental degradation

Mayflies are threatened by pollution, invasive species, habitat loss, and climate change. Some species of mayflies in North America are already extinct, and others are endangered.

Mating

Mayflies mate in midair, with the female laying thousands of eggs in the water after mating.

Lifespan

Adult mayflies, also known as spinners, have no mouth parts and cannot eat, so they usually only live for a single day.

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Mayflies (Ephemeroptera) and Their Contributions to Ecosystem Services

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This work is intended as a general and concise overview of Ephemeroptera biology, diversity, and services provided to humans and other parts of our global array of freshwater and terrestrial ecosystems. The Ephemeroptera, or mayflies, are a small…

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try out my mayfly quiz and test what youve learned.