What Does a Mayfly Look Like? Unveiling Nature’s Ephemeral Beauty

Mayflies are fascinating insects with unique appearances. When you come across a mayfly, you’ll notice its slender, soft body, and four membranous wings. These wings, which are held upright and together, have extensive veins and differ in size—the forewings are much longer and often overlap the hindwings 1.

As you observe a mayfly more closely, you might find its short antennae and large compound eyes to be striking features. Additionally, two long, threadlike cerci extend from its rear end, giving it a distinctive and delicate look 1.

These charming creatures are an essential part of aquatic ecosystems, contributing to essential ecosystem services. So, the next time you encounter a mayfly, take a closer look and appreciate its delicate beauty 2.

Mayfly Overview

Mayflies are fascinating insects belonging to the order Ephemeroptera. They can be found worldwide and play an essential role in their ecosystems. With over 3,000 known species within this order, these unique insects exist in a variety of habitats.

As an adult mayfly, you’ll have a slender, soft body with large compound eyes. Your four membranous wings will be held upright and together, giving you a beautiful butterfly-like appearance. Your front pair of legs may extend outward when perching, and you’ll possess two long, threadlike cerci at the tip of your abdomen.

Now, imagine yourself as a mayfly nymph. You’ll spend most of your life underwater, where you’ll go through several molts to grow. Some mayfly nymphs are excellent swimmers, like the Baetidae family, while others like the Heptageniidae family are commonly found in flat habitats.

Key features of mayflies include:

  • Slender, soft bodies
  • Four membranous wings
  • Large compound eyes
  • Two long cerci at the tip of the abdomen
  • Distinct nymph and adult life stages

In conclusion, mayflies are unique insects with thousands of species belonging to the class Insecta and phylum Arthropoda under the kingdom Animalia. They have a distinct and interesting appearance, whether in their adult or nymph stage. Their fascinating life cycle and ecological significance make them an essential part of the natural world.

Physical Appearance of Mayflies

Body Structure

Mayflies have a slender and soft-bodied structure. Their head features large compound eyes and short antennae. The thorax connects the head to the abdomen, which has long, threadlike cerci. These insects can vary in size, with some species being small enough to fit on your fingertip.

Color Patterns

The colors of mayflies can differ among species. They can be found in shades of gray, brown, and even muted greens. This variation mainly serves as camouflage, helping them blend in with their surroundings. Some mayflies sport additional markings or patterns on their bodies.

Wings and Tails

Mayflies have four membranous wings that are extensively veined. Their forewings are usually longer and often overlap the hindwings. When at rest, they hold their wings upright and together, resembling a butterfly’s stance. Along with their wings, mayflies have two or three long tails that extend from their abdomen. These tails help them maintain balance while flying and navigating their environment.

In summary, mayflies have a unique and delicate appearance. Paying attention to features such as their body structure, color patterns, wings, and tails can help you identify these fascinating insects.

Mayfly Life Cycle

Nymph Stage:
Mayflies begin their life cycle as a nymph, also known as a naiad. These aquatic creatures have a body length of up to 35 millimeters and can be green or brown in color. They possess long legs, plate-like gills, and short antennae. Some distinguishing characteristics of mayfly nymphs include:

  • Three long thin tail projections (cerci)
  • Flattened forms that attach themselves to rocks or other surfaces
  • Ability to swim very fast, like the Baetis nymph

Molting and Subimago Stage:
As the nymph matures, it undergoes molting to shed its exoskeleton and grow. During the molting process, the mayfly briefly enters the unique subimago stage, an intermediate step between the nymph and adult stages. In this stage, the mayfly is winged but sexually immature. It appears duller in color compared to the final adult stage.

Adult or Imago Stage:
After the subimago molt, the mayfly reaches its adult stage, or imago. Adult mayflies are typically slender and soft-bodied. They have four membranous, extensively veined wings held upright and together, similar to a butterfly. The forewings are longer than the hindwings, and they often overlap. The front pair of legs are usually held outward while perching. Their large compound eyes and short antennae also characterize them.

It’s crucial to understand that the entire mayfly life cycle is relatively short. While the nymph stage lasts for about a year, the adult stage occurs over just a few hours to a couple of days. The primary purpose of an adult mayfly is to mate and reproduce, so once its mission is accomplished, its life comes to an end.

Habitat and Distribution

Geographical Spread

Mayflies are predominantly found in North America, inhabiting various freshwater environments. Their distribution ranges from small streams to large rivers, but they tend to favor unpolluted waters. To give you an idea:

  • Found across North America
  • Thrive in unpolluted freshwater

Types of Habitats

These delicate insects are commonly associated with aquatic habitats, where they spend a majority of their life cycle. They typically inhabit two main types of habitats:

  1. Streams: Mayflies are often seen in flowing waters such as streams, where they contribute to the ecosystem by serving as a food source for other organisms.
  2. Rivers: Larger, fast-flowing rivers also accommodate mayflies; their presence in these habitats can be an indicator of good water quality and a healthy ecosystem.

In both streams and rivers, they prefer unpolluted waters with rich oxygen content. The brown color of their nymph stage helps them blend into their surroundings, making it challenging to spot them at first glance. But with an understanding of their habitat preferences, you’ll know where to look!

Just to recap, mayflies can be found in:

  • Aquatic habitats, specifically streams and rivers
  • Unpolluted, oxygen-rich environments
  • Brown nymphs blend into surroundings

Feeding Habits of Mayflies

Mayflies are fascinating insects that play a crucial role in freshwater ecosystems. When it comes to their feeding habits, mayflies predominantly feed on algae, detritus, and other organic matter in their surrounding environment. Let’s explore a bit more about their diet.

As nymphs, mayflies are known to consume a variety of organic material. They tend to primarily feast on algae, which provides essential nutrients for their growth and development. Some species prefer to graze on the fine particles of organic matter, called particulate organic matter (FPOM) source.

It’s worth noting that the feeding preferences of different mayfly species can vary. A good example of this can be observed with the Oligoneuridae family of mayflies. These insects are adapted to filter-feed, using the long setae on their first pair of legs to sift FPOM from the water source.

In addition to algae and detritus, mayflies also help regulate the populations of smaller invertebrates by feeding on them. This is particularly relevant when discussing the role mayflies have in maintaining a balanced ecosystem.

Overall, understanding the feeding habits of mayflies can provide valuable insights into their contributions to ecosystem services, particularly in terms of regulating algal growth and cycling nutrients – all while maintaining the delicate balance that exists in aquatic habitats source.

Reproduction and Mating

In the world of mayflies, reproduction and mating are quite fascinating. These insects display unique behaviors, with males forming swarms to attract females. Once the female flies into the swarm, she mates with a male and starts the process of laying eggs in a suitable aquatic habitat.

Mayflies exhibit sexual dimorphism, which means males and females look different from each other. For instance, you might notice that males have larger eyes compared to females. This feature helps them locate and attract potential mates in their short lifespan.

During mating, mayflies display an intriguing phenomenon known as the spinner stage. This is when adult mayflies transform into a more mature form, shedding their exoskeleton to reveal a more vibrant, yellow color. This process shows that they are ready for mating and have reached their final life stage.

To help you better understand the characteristics of mayfly reproduction and mating, here is a list of key features:

  • Males form swarms to attract females
  • Females lay eggs in aquatic habitats
  • Sexual dimorphism in size and appearance
  • Spinner stage indicates readiness for mating
  • Bright yellow color signals maturity

As fascinating as mayfly reproduction may be, it’s essential to note that their adult lives are incredibly brief. Thus, they must complete the entire process of mating and laying eggs within a day or two. This ephemeral nature is why they are called “mayflies” or Ephemeroptera. So, when you see these insects perform their mating rituals, appreciate the beauty and intriguing nature they bring to the ecosystem.

Role in Ecosystem

Mayflies play a vital role in both freshwater and terrestrial ecosystems. They are an essential food source for various predators such as birds and fish. For example, the decline of mayflies can affect the survival and breeding success of birds, like swallows and other insect-eating species. These insects are also an essential part of the diet of many aquatic organisms like fishflies and larger fish.

Being sensitive to changes in water quality, mayflies serve as bioindicators, which can help in conservation efforts. A healthy population of mayflies indicates good water quality, while their absence signifies deteriorating environmental conditions in the aquatic ecosystems. By monitoring the presence and population of these insects, scientists and conservationists can identify the areas that need intervention and improved water management.

When it comes to recreational activities like fishing, mayflies can be beneficial too. For instance, anglers use lures that mimic the appearance of mayfly nymphs or adults, as they are an irresistible bait for many fish species. In this sense, their presence in the water can also indicate an abundant fish population that attracts anglers to the area.

In summary, the presence of mayflies is essential to the balance and health of aquatic ecosystems. They serve as a food source for various predators, help us understand and protect water quality, and even contribute to recreational activities like fishing. By understanding their role in ecosystems, we can ensure their conservation and maintain ecological harmony.

Interactions with Humans

Mayflies, while generally harmless, can sometimes become a nuisance for humans. They are typically found near bodies of water where they lay their eggs, leading to increased interactions with people living nearby.

In some cases, mayfly swarms have been known to disrupt daily activities. For example:

  • Mayflies are attracted to light, so they can gather around streetlights or the lights on your porch, making it difficult to see or navigate through the swarm.
  • Their short life span can cause a sudden influx of dead insects, leading to unpleasant smells and the need for cleanup.

Pros and Cons of Mayflies:

  • Pros: They are an important food source for fish and other aquatic species, and they can indicate the health of an ecosystem.
  • Cons: They can become a nuisance for humans when they gather in large numbers around light sources or when their dead bodies accumulate.

When you encounter mayflies, remember to keep your distance and turn off outdoor lights if possible to discourage them from gathering near your home.

Taxonomy and Classification

Mayfly Orders

Mayflies belong to the order Ephemeroptera within the class Insecta of the phylum Arthropoda. They are not the same as butterflies, beetles, or dragonflies. Invertebrates like mayflies have a unique appearance and lifecycle. Here are some features of mayflies:

  • Adult mayflies have two or three long, thin tails
  • They possess large, transparent wings that are held upright when resting
  • Mayflies have short antennae
  • Their mouthparts are vestigial, as adult mayflies do not eat

Mayfly Families

There are several families within the order Ephemeroptera, including Baetidae and Ephemeridae. These families are often referred by common names such as shadflies or dayflies. Here’s a brief comparison of the two families:

Baetidae Ephemeridae
Common Names Small Minnow Mayflies Common Burrower Mayflies
Habitat Prefer clear, fast-flowing waters Inhabit still or slow-moving waters
Larval Appearance Slender and agile larvae with short tails Burrowing larvae with long, strong legs

Remember, your study of mayflies is not limited to these two families. There are over 23 families and 108 genera of mayflies currently recognized in North America. So, keep exploring and learning about these fascinating insects!

Unique Features and Behaviors

Mayflies, also known as duns or drakes, are fascinating insects with a variety of unique features and behaviors. Let’s explore some of their interesting characteristics.

Mayflies begin their lives as aquatic larvae called naiads. These underwater creatures are well-adapted to their surroundings with gills for breathing and specialized mouthparts for feeding. They even have legs with claws and bristles to help them move and cling to debris in their environment. These adaptations ensure their survival in clean, non-cloudy water, making them an indication of good water quality.

Adult mayflies exhibit certain distinctive physical traits as well. They are slender and soft-bodied insects with four membranous wings, held upright together, resembling a butterfly’s posture. Their large compound eyes, short antennae, and two long, threadlike cerci (antenna-like appendages) at the tip of their abdomen make them stand out among other insects.

In addition to their intriguing physical features, mayflies exhibit an unusual life cycle that includes a subimago stage. This stage, which is unique to mayflies, takes place between the larval instar and the mature adult stage, or imago. During the subimago stage, the insects are active and mobile, undergoing one final molt before they reach sexual maturity as imagos.

Here’s a quick comparison of mayfly stages:

Stage Features Behavior
Naiad Gills, specialized mouthparts, legs with claws and bristles Aquatic, clings to debris
Subimago Similar to imago, but not sexually mature Active and mobile, molts one more time
Imago Slender, soft-bodied, 4 wings, short antennae, large eyes, cerci Reproduces, short-lived

So there you have it, a brief overview of the unique features and behaviors of mayflies. From their underwater beginnings as naiads to their multistage metamorphosis and distinctive adult appearance, these insects are a fascinating study in adaptation and survival.


  1. https://mdc.mo.gov/discover-nature/field-guide/mayflies 2

  2. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6628430/

Reader Emails

Over the years, our website, whatsthatbug.com has received hundreds of letters and some interesting images asking us about these insects. Scroll down to have a look at some of them.

Letter 1 – Mayfly


Strange Fly
I recently encountered this large fly on my honeymoon in Alexandria Bay, in the Thousand Islands region of New York. It was sedately sunning on my balcony until I started trying to get close enough to take a macro mode shot. It began lifting it’s mandibles and whip-like in threatening(or inquisitive) ways at me. It was quite a show, and if the display was for purposes of intimidation I would say it suceeded! I should’ve taken a quick movie clip of it, but these pics will have to suffice…. So, what’s that bug?
-Ben H.
P.S…. And, no, I didn’t kill it! Though if it were inside I probably would have. Just to prove I wasn’t scared.

Hi Ben,
Mayflies in the order Ephemeroptera, are totally harmless. Adults do not even possess mouthparts as they only live a few days and their sole purpose is to mate, (except to provide food to other creatures including trout).

Letter 2 – Mayfly


What is this bug?
Location: Huntsville, AL
April 9, 2012 5:19 pm
I was out fishing and this bug landed on my jacket. I have never seen anything like it.
Signature: Liz S


Hi Liz,
This interesting creature is a Mayfly in the insect order Ephemeroptera.  Mayflies do not feed as adults, and they only live a few days, long enough to mate and lay eggs.

Letter 3 – Mayfly


Subject: A bug we found on the door.
Location: Carmel, NY
July 8, 2012 11:09 am
We found this bug on the door, I have never seen anything like it. It reminds me of a centipede the way it has the tendrils on the back.
Signature: Jeremy Currier


Hi Jeremy,
This is a Mayfly and they are often attracted to lights.  They can appear in prodigious numbers.  They are generally found near water because the nymphs are aquatic.

Letter 4 – Mayfly


Subject: Unusual N. Mississippi winged bug
Location: N. Mississippi just outside of Memphis, Tn.
July 9, 2012 5:36 pm
Love your site!! This bug was on our outside redneck fridge. I have never seen one before or since. Could you please identify?
Thank you
Stephanie Berry


Hi Stephanie,
We really need to know if the redneck fridge is full of beer.  This is a Mayfly, a common group of insects often found near water where the aquatic nymphs or naiads develop.  Adults are often attracted to lights.

Fridge = BEER!@
And, we have a small lake out back.
Right now I’m nursing a Copperhead bite.
Y’all come on down for some Beer and bugs!  LoL
Thanks for the info … y’all are amazing!
Stephanie Berry

Thanks for the invitation Stephanie.  We just might take you up on that offer some day.

Letter 5 – Mayfly


Subject: Help ID these bugs
Location: Maryland
May 14, 2013 4:08 pm
We have these every year on the side of the house. They seem to like the shade. They don’t appear to an issue. There’s just alot of them. I haven’t been able to ID them.
Signature: Mike


Hi Mike,
You must live near a source of fresh water.  This is a Mayfly and they have aquatic larvae.  When it is time for metamorphosis to the winged adult, they often emerge in large numbers.  Mayflies to not eat as adults, and generally live a few days at most, long enough to mate and reproduce.

Letter 6 – Mayfly


Subject: My Friend Made a Creepy Friend At Work
Location: Chatanooga, TN
July 26, 2013 7:04 am
My friend works at a restaurant and found the attached little guy just chilling on her prep work table. She said that he didn’t seem to be in a hurry to move, even when she poked at him – he jumped a little and vibrated his wings, but that was about it. They ended up gently corralling him into a paper cup and putting it back inside, but we have exhausted our Googling to figure out what this cool thing is!
Signature: Heather


Hi Heather,
This is a Mayfly, and we have an extensive archive of photos of Mayflies with much information.

Letter 7 – Mayfly


Subject: Yellow and Black with a whip tail
Location: Pittsburgh, PA
July 11, 2014 7:51 pm
Dear Bugman:
A friend found this bug on her windshield wiper. It was at night on July 11, 2014.
Thanks in Advance!
Signature: Curious Mark


Hi Curious Mark,
This is a Mayfly in the order Ephemeroptera, and we are speculating that you are near some body of water as the Mayfly nymphs or naiads are aquatic, and adults are feeble fliers that do not travel great distances.

Letter 8 – Mayfly


Subject: Weird bug looks like cross between mantis and dragonfly
Location: South Texas
August 10, 2014 9:17 pm
My neice and I were out swimming at a small lake in south Texas when this incredibly odd looking bug landed on my hand. I called my neice over and we looked at it for a while, neither of us being able to identify it. I brushed it off my hand, only to find it about an hour later hanging off the side of her drink, where I snapped this picture.
I’m incredibly interested in finding out what this crazy looking bug is! Thanks in advance!
Signature: Leah


Dear Leah,
This Mayfly is in the order Ephemeroptera, and it is not closely related to either Mantids or Dragonflies.  Mayflies are generally found close to water sources as the nymphs are aquatic.  Mayflies do not feed as adults, and larger Mayflies are prized bait for fly fishers who also tie flies to mimic Mayflies.

Letter 9 – Mayfly


Subject: Peculiar flying bug in Wroxham, England
Location: Wroxham (a town in Norfolk in the East of England)
June 1, 2015 6:02 am
Hi. I hope you can identify this strange creature. On 13 May2015, my wife and I hired a small boat at Wroxham which is a small town in Norfolk in the East of England. A flying bug landed on the boat’s windscreen and stayed there long enough for me to take these photos. It was about an inch in size. The photos were taken through the glass windscreen which enabled me to have this unusual ‘from below’ view. I’ve never seen anything quite like this bug before! Thank you.
Signature: Robin Groen


Dear Robin,
This Mayfly in the order Ephemeroptera has an aquatic nymph, so adults are rarely found far from water as their flight is rather feeble.  Mayflies often emerge in great numbers to mate as they only live a few days.  They do not feed as adults.

Letter 10 – Mayfly


Subject: Flying River Insect
Location: Louisville, Kentucky (riverside)
June 27, 2016 3:43 pm
Dear Bugman,
Yesterday, June 26th, as I drove to the edge of the Ohio River, in Louisville, Kentucky, a small swarm of these dragonfly like insects landed all over my car. I actually had one that took a ride to the grocery store with me, afterward! I suspect that they were juvenile dragonflies. Can you confirm?
Signature: Waterwatcher


Dear Waterwatcher,
This is a Mayfly and they can get very numerous at times.


  • Bugman

    Bugman aka Daniel Marlos has been identifying bugs since 1999. whatsthatbug.com is his passion project and it has helped millions of readers identify the bug that has been bugging them for over two decades. You can reach out to him through our Contact Page.

  • Piyushi Dhir

    Piyushi is a nature lover, blogger and traveler at heart. She lives in beautiful Canada with her family. Piyushi is an animal lover and loves to write about all creatures.

Leave a Comment