The Mayfly
The Mayfly

Scientific Name: Hexagenia

Kingdom: Animalia

Phylum: Anthropoda

Class: Insecta

Order: Ephemeroptera 


Physical Appearances-

A Mayfly Nymph
A Mayfly Nymph
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The first physical stage of the Mayfly's life is the nymph, or the larvae stage. Mayflies are nymphs because they go through many instars and molts, also because they go through gradual metamorphosis. When hatched, the nymphs are less than a 1 mm long. Their specific body shapes depend on the habitat in which they are born. (For example, some have more cylindrical bodies because they are born in burrows rather than under a rock which would cause them to have a more flattened body structure.) The nymphs can grow to be 3 to 4 mm in length during this stage of life. On each segment of the abdomen are a pair of gills. This structure is found on the nymphs as they age. The gills extend from their sides and are in an oval-like shape. The size of the gills, like the body shape, depends on the habitat. (For example, if the nymphs are in still water the gills are larger, however, they are smaller when the nymphs are in running water.) Nymph's gills are not just for taking in oxygen like that of most organism that obtain them, but rather these gills push water out in several different directions. Larger gills mean the nymph can move more rapidly through the water. This creates a natural protection quality for the nymphs because they are less likely to be able to be traced by predators. Male nymphs have clasping organs on the lower portions of their abdomen. Also, the males have a special feature of having a divide in their eye, which can be seen with the two different colors of the eye. These two sections of the eye have different functions which are to see movement and to see details. On the other hand, females have smaller eyes as well as oviducts in the lower abdomen. In the last stage of the nymph cycle, the nymphs develop their wings, which have tiny hairs all over them. In addition, these tiny hairs are all over the body. The wings are dull and are tinted with some pigment. This is the nymphs' entry into adulthood.
Adult Mayfly
Adult Mayfly
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Now that the mayflies are matured into adults, their physical appearences start to change yet again. The legs and tails of the mayflies start to lengthen and grow. In the final adult stage, the mayflies wings are now shiny and hairless. The wings are very triangular and membranous and are held up just like those of the butterflies. A cloudy or see through color is often what the wings are seen as. They have a pair of hindwings which are much smaller than the forewings. The second segment of the thorax is larger for it contains most of the flight muscles.Tails of the mayflies, or cerci, extending from the end of their abdomens. Some species only have two tails, but the majority of the different species have three tails. Adults have three ocelli and have two flexible, short antennae. The mayflies are usually colored around the shades of white, brown, yellow, or green depending on the species. Male and female mayflies differ physically apart from their genitalia. In most females, all of their legs are atrophied, whereas only the hind legs are atrophied on males.

Distinguishing Characteristics

Mayflies have unique traits that are different than those of the similar bugs. Stoneflies and Damselfies are often mixed up with the mayfly because of the general similar structure. However, the placement and structure of the parts of these insects are not the same. Mayflies have fringed gills on their abdomen instead of finger-like gills. Their mouth parts are classified as chewing and they only have one claw. However, their mouth parts do not actually fully develop because of their feeding habits. They usually have two or three tails that are of the filamentous shape.


The mayflies enjoy freshwater environments. These environments are usually cooler and the water can be of any level. However, most of the nymphs are
Mayfly Habitat
Mayfly Habitat

found in the shallow parts of lakes or creeks. In shallow water the oxygen content is the highest. The water in which they live must be well-oxygenated and relatively free of pollution. The adult mayflies are usually found near vegetation and are attracted to lights. The nymphs can usually be found under decaying plants, mud, and other particles on the bottoms of the body of water. Common places to find mayflies are in mountain streams and in higher altitude places because of the neutral temperatures.

Factors Among Habitats

Habitats vary for different species of mayflies. Some mayflies perfer running water over still water. Other factors influencing the choice habitats of this bug are temperature of the water, chemicals in the water, and the amount of sunlight available for them.

check out this podcast of exploring mayflies! (this brings you to the site, click play)

Geographic Range

Mayflies have about 2,500 species ranging all over the world. 630 of those species are found on the continent of North America. They are found on all continents except for Antarctica and on a few small inslands where the climate starts to become more frigid. Mild and tropical areas are where they range the most. For example, Australia is an area that holds many mayflies.
Shaded in states are where the mayflies can be found in the United States and parts of Canada. Mayflies come around for different seasons in each state.
Areas of the United States and Canada that have Mayfly population
Areas of the United States and Canada that have Mayfly population
Map of where mayflies can be found around the world
Map of where mayflies can be found around the world

The two maps above show where mayflies are present. The first map on the top, shows which specific states in the United States including parts of Canada in which mayflies live. The areas of mayfly population are shown in the second map. On the second map, it shows the broad areas of the world. Mayflies generally live where there is water. However, Antarctica is not included because of the freezing temperatures of water.

Mating Behavior

Mating occurs after the last malt of the mayflies. During this mating process, the male mayflies start off by performing a mating flight which is a dance for
Two Mayflies Mating
Two Mayflies Mating
the females to soon take part in. This swarm of males is usually seen over water at dusk. The individuals move through the air in a repeating pattern of floating downward and then floating back up. Soon after, the females make their way into the swarm and continue the pattern of falling and rising. Male mayflies then go behind the females to take hold of their thorax with their front legs. Sperm is transferred directly to the female's genitals, fertilizing her eggs.They generally mate on wing, in the air, with the male underneath. While physically mating, the mayflies will either continue to fly or hover over the water getting out of any harsh winds. Once the male has fertilized the female's eggs, he will stick with the female to assure that no other male tries to mate with her. The females then fly lower and closer to the water to release the quickly fertilized eggs. She drops her eggs a few at a time while moving along the water's surface.

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Life Cycle

Mayflies have a very short but interesting life cycle. This life cycle consists of four stages- egg, nymph, subimago, and imago. Although their life outside of water as adults lasts only a day or two, the process of becoming fully matured takes time. A common name for Mayflies is Ephemerids because of this living in an aquatic state compared to nonaquatic state ratio.


After the mother mayfly drops her eggs into the water, the eggs wash off the sticky substance remaining after the birth. Females will p
Mayfly Eggs
Mayfly Eggs
roduce 50 to 10,000 eggs. Once laid in water, these eggs sink to the bottom or attach themselves onto objects in the water like docks, rocks, and debris. Mayfly eggs will hatch in about two weeks after being laid, however, in some cases eggs can go into a state called diapause where no growth occurs. This is an adaptation that the eggs go through to prevent hatching in an environment not suitable for the stage of being nymphs.


The nymph stage can last for two week or up to as long as two years depending on the mayfly. However, the average is about a year. During this time about 50 molts may occur. At this time they have seven pairs of gills on their abdomens. The dark wing pads become visible and soon they will molt to develop their wings. After the nymphs are able to mature slightly, they can start to move around in the water stalking up on food.
Mayfly molting
Mayfly molting
Eventually the nymphs swim to the surface of the water to prepare for their next molt which is subimago. The nymphs climb up on rocks and other dry surfaces to break out of their nymph skin.


In this stage, wings are formed and are out of the skin in which they were held back in. The subimago stage is very dull in the appearance of mayflies and it is extremely quick. Depending on the species, this stage can last a few minutes to 48 hours. It is mostly a transition molt into the imago stage which is the final adult stage. Legs of the mayflies are often short in this stage and are in the process of growing along with the rest of the body. The wings become stronger and extend more along with the legs, and the color of the mayflies start to appear. In contrast, when the mayflies hit this stage their mouth parts become disabled and their digestive system does not develop any further. Once the wings dry and the skin of the mayfly is completely off the it will fly to near by vegetation. While in this state, the mayfly is known as a mayfly "dun".


Now in the imago stage of life, the mayflies are fully adults. They molted once again to change from mayfly "duns" to mayfly "spinners". Their bodies are more shiny with longer tails and legs. Imago is the reproductive stage of this insects life. The mayflies go into the swarm dance at dusk finding mates. (This process of mating said above in mating behaviors) Once successfully mated, the male goes off with little energy left and dies. On the other hand, the female has one more job to complete. With the new fertilized eggs, the mother lowers her abdomen into the water and releases the eggs. Sometimes this takes so much energy that she dies in the process. However, if she is still alive, like the male, she will go off and slowly die. Over all, the mayflies usually only live a day once they are out of the nymph stage which is why they often get nicknames meaning short lived.

Feeding Habits

Mayflies only feed while they are in the stage of being nymphs. The nymphs are still in an undeveloped stage because in this stage they do not start to molt. They are underwater where most often they feed off of algae, a
very common resource in their habitats. While taking in algae, the nymphs take in other microscopic organisms as well. These microorganisms can be found other places in the water, which sometimes leads the larvae into eating the remains of aquatic animals such as fish and turtles. To physically consume the food, the nymphs must move their gills to suck in water, containing particles of algae and other microscopic products. Some nymphs even use their temporary mouth parts to scrape algae off of different aquatic settings and to take nutrition from the decaying animals.

Reason for Feeding Habits

Mayflies feed vigorously as nymphs when they are not even developed into a molting form yet. However, there is a reason for this. The nymph stage needs to consume an abundance of energy to power up for the on coming stages. It takes loads of energy to undergo the complex transformations their bodies undergo.

Ecological Role

Mayflies have an important ecological role. The mayfy nymphs play a specific role in the ecosystems of many freshwater bodies. These nymphs graze and consume large amounts of algae and other build ups of organic particles in the water. This helps the water maintain its nutrience cycle and not become
Mayflies swarming over lake indicating good water:)
Mayflies swarming over lake indicating good water:)
too polluted with fast spreading organisms like algae.Mayflies help determine the water quality because of their toleration and intoleration of different habitats. These insects will not be able to survive in an area or body of water that is too polluted. If the water has too much organic debris, it is not considered good quality water. However, if the water is fresh, oxygenated, and clean then the mayflies will be full of life and will be in groups of numerous amounts. Ecologists will often look to the mayflies to know the condition of the water. Mayflies are also very abundant in their habitat, providing food for many predators. Although aquatic organisms may consume the many other aquatic creatures, the mayflies are easy to catch because of their liking of being around water, as well as spending their life in water too. Trout and salmon depend the most on mayflies for food. Some other significant predators are birds and dragonfly nymphs. When the mayflies died, they lay themselves in the water. This is easy and free food for the predators to get, supporting many organisms. Ultimately, this role benefits the food chain.

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