Exploring the Natural Predators of Mayflies

Mayflies are fascinating insects that play an essential role in their ecosystem. These delicate creatures emerge in large numbers and live for just a short time, attracting the attention of various predators. As you explore the world of mayflies, you’ll discover the different creatures that rely on them for sustenance.

In the aquatic environment, mayflies begin their lives as nymphs. During this stage, they already have a few natural enemies. For instance, the naiads of common green darners are known to eat mayflies along with small fish and tadpoles. As mayflies transform into adults and take to the skies, they become a favored food source for even more predators.

Among the airborne hunters of the insect realm, dragonflies and damselflies are adept at catching mayflies in flight. Furthermore, other opportunistic predators like birds and bats often feast on mayflies when they’re available. So, as you delve deeper into the diet of various creatures, it becomes clear how important mayflies are in maintaining the balance of their natural habitats.

Understanding Mayflies

Mayflies, also known as Ephemeroptera, are a unique order of aquatic insects. These fascinating creatures have a distinct life cycle, including a subimago stage between the ultimate larval instar and the mature adult stage, or imago. Let’s take a closer look at their biology and significance in the ecosystem.

At the adult stage, mayflies are delicate and slender with four membranous wings. Their wings are veined and held upright, resembling a butterfly. Mayflies have short antennae and large compound eyes. You can often see them with two long, threadlike cerci extending from their abdomen tip. Some key features include:

  • Slender body
  • Four membranous wings
  • Short antennae
  • Large compound eyes

Mayflies play a critical role in aquatic ecosystems, particularly during their nymph phase, where they have gills and live exclusively underwater. Nymphs consume algae, plant material, and even each other. In this stage, they become vital food sources for fish and other animals further up the food chain. (source)

Their habitat ranges from rivers and streams to ponds and lakes. Mayflies require clean water to thrive, so their presence is considered an indicator of good water quality. If your local water bodies are home to mayflies, it’s a positive sign of a healthy aquatic ecosystem.

Take a look at this comparison table to understand their role in the food chain:

Stage What They Eat What Eats Them
Adult Mayfly None Birds, Bats
Mayfly Nymphs Algae, Plants, Dead Leaves, Wood, Other Nymphs Fish, Other Aquatic Insects

In conclusion, understanding mayflies, their unique life cycle, and their essential contributions to the aquatic ecosystem will help you appreciate their presence and the vitality of the water they inhabit. So, the next time you spot a mayfly, take a moment to consider its important role in maintaining healthy waterways.

Lifecycle of Mayflies

Mayflies are fascinating insects with a unique lifecycle that includes a stage called the subimago. In this stage, they are active and mobile, existing between their ultimate larval instar and the mature adult stage, or imago [^1^]. Let’s dive into various stages of their lifecycle to get a better understanding.

Eggs: Mayflies begin life as eggs, laid by females in freshwater environments. Once laid, the eggs sink to the bottom of the water and eventually hatch into larvae [^2^].

Larvae: After hatching, mayfly larvae (also called nymphs) live underwater for weeks to months, depending on the species. Here, they feed and grow, molting several times as they develop [^3^]. Some key features of mayfly larvae include:

  • Gills for underwater respiration
  • Specialized mouthparts for feeding on plant matter and other organic materials

Subimago: The subimago stage, unique to mayflies, is reached after the last larval molt. This stage is short-lived, usually lasting only a few hours to a day [^4^]. During this time, subimago mayflies perform a quick mating dance before molting once more to become imagos.

Imago: The final and reproductive stage of a mayfly’s life is the imago. Here, males and females mate, often in large swarms, resulting in fertilized eggs that will ensure the continuation of the species [^5^]. Some characteristics of adult mayflies include:

  • Wings held upright when at rest
  • Two long cerci, or antenna-like appendages, at the tip of their abdomen

It’s worth noting that the lifespan of adult mayflies is incredibly short, ranging from just a few hours to a couple of days [^6^]. During this time, they focus solely on reproduction, as they don’t even have functional mouthparts for eating.

By understanding the lifecycle of mayflies, you can better appreciate their unique biology and the role they play in freshwater ecosystems.

Physical Characteristics of Mayflies

Mayflies are delicate insects with some unique features. Their size and color can vary depending on the species, but generally, they have slender bodies and large eyes.


  • Mayflies have four wings, which are membranous and extensively veined.
  • Their triangular front wings are larger and often overlap the smaller, rounded hind wings.

Antennae and eyes:

  • Antennae on mayflies are relatively small.
  • Their compound eyes are large and well-developed, helping them navigate their environment.

Tails and gills:

  • Typically, mayflies have two long tails, also known as cerci, that extend from the tip of their abdomen.
  • Some species also have an additional central abdominal filament, giving them three tails.

These physical features not only make mayflies easily identifiable, but they also play a crucial role in their life cycle, attracting mates and helping them survive in their aquatic habitat.

Behavior and Habits of Mayflies

Mayflies are fascinating insects with unique habits and behaviors. Let’s explore some of these interesting aspects:

Swarming: Mayflies often gather in large groups called swarms. These swarms typically occur near water bodies and can be an amazing sight, as well as an indication of a healthy aquatic environment.

Resting and Activity Periods: Mayflies are most active during the day, resting at night. Their short life spans, ranging from just a few hours to a few days, make their activity periods crucial for reproduction and finding mates.

Attraction to Light: Like many other insects, mayflies are attracted to lights at night. This behavior can cause them to gather around streetlights and other sources of artificial light, sometimes in large numbers.

Seasonal Trends: Mayflies live primarily in the warmer months of the year, with their populations peaking during the summer. This is due to increased availability of food, as well as optimal water temperatures for their growth and development.

Here are some key features of mayflies:

  • Short life spans (a few hours to a few days)
  • Attraction to light sources
  • Swarming behavior
  • Active during the day, resting at night
  • Population peaks in the summer

Remember, understanding the behavior and habits of mayflies can help you appreciate their role in the ecosystem and increase your awareness of the world around you. Enjoy observing these fascinating creatures in their natural habitats, and always approach with a friendly and respectful curiosity.

Mayflies as Prey

When it comes to mayflies, they play a significant role as prey in various ecosystems. Many animals rely on them as a food source, making them an essential part of the food chain.

For instance, fish like trout love feasting on mayflies. When mayflies emerge from the water for their brief adult life stage, their presence often triggers a feeding frenzy among fish.

Apart from fish, birds are also known to prey on mayflies. As these insects swarm near water bodies, they attract a variety of avian species such as swallows and swifts. This also contributes to controlling their population.

Other predators of mayflies include dragonflies, frogs, and snails. In fact, dragonflies are well-equipped to hunt and catch mayflies in mid-air. Their agile flight and accurate hunting skills allow them to target and consume these insects with ease.

When comparing some of the most common predators of mayflies, here’s a simplified table:

Predator Location Predation Technique
Fish In Water Feeding on emerging mayflies
Birds Near Water Catching swarming mayflies
Dragonflies In Air Hunting mayflies mid-flight
Frogs & Snails Along the water’s edge Ambushing or consuming aquatic nymphs

In conclusion, many animals benefit from the presence of mayflies, whether they live in the water, near the water’s edge, or even in the air. Their unique life cycle provides an important food source for a variety of species and further enriches the delicate balance of freshwater ecosystems.

Mayflies in the Ecosystem

Mayflies are interesting creatures that play an important role in various ecosystems. They can be found in freshwater environments like streams, lakes, and ponds, as well as in forests near these water bodies. Mayflies are often used as indicators of water quality because they are sensitive to changes in their surroundings.

These insects have a unique life cycle, including a subimago stage between the larval and adult stages. In this stage, they are mobile and active, contributing to the ecosystem in various ways. For example, mayflies provide nutrients to the environment when they die and decompose, releasing minerals back into the water and soil.

As for what eats mayflies, they serve as an essential food source for many species in their natural habitats. Various animals, such as fish, birds, and amphibians, feed on mayflies in different life stages. This consumption also helps to control the mayfly population, maintaining a balance within the ecosystem.

Some of the key features of mayflies and their role in the ecosystem include:

  • Indicator of water quality and river health
  • Sensitive to changes in the environment
  • Provide nutrients to the ecosystem when they decompose
  • Serve as a food source for many species, including fish, birds, and amphibians

So remember, when you see mayflies near freshwater environments, they are not just beautiful insects, but also essential contributors to the ecosystem. Keep that in mind and nourish your appreciation for their presence in our beautiful world.

Threats to Mayflies

Mayflies are an important part of aquatic ecosystems and face various threats from predators and parasites. In this section, we will discuss some of the threats that mayflies encounter in their environment.

Predators of mayflies come in many forms. Aquatic invertebrates such as naiads and other insects are known to prey on the mayfly nymphs, while birds, bats, and fish target adult mayflies. Even some mammals, like small rodents, will consume mayflies. These predators help control the mayfly population, and their presence indicates a healthy ecosystem.

In addition to predators, parasites like nematodes and trematodes can also be a threat to mayflies. These parasites can infect mayflies throughout their life cycle, causing harm or even death to their hosts. One example is the Paragordius varius, a hairworm parasite that can infect mayfly nymphs and manipulate their behavior to induce them to jump into water, where the parasite can complete its life cycle.

To summarize, mayflies face various threats from predators such as invertebrates, birds, and fish, as well as parasites like nematodes and trematodes. However, these interactions are all part of a natural and healthy ecosystem, as mayflies serve as food sources and indicators of water quality.

Mayflies and Humans

Mayflies are an important part of both freshwater and terrestrial ecosystems, providing several benefits to humans and other organisms. They are particularly important in the conservation of biodiversity in North America and around the world.

You might have seen an increase in the number of mayflies around your buildings during certain times of the year. This is perfectly normal, as they are attracted to lights and wind can also bring them to urban areas. Don’t worry, these insects are not harmful to people or structures.

In the United States and other regions, they serve as a key part of the food chain. For example, their immature stage, known as nymphs, consumes algae and debris in the water. In turn, they become an important food source for fish and other aquatic animals. This relationship emphasizes the importance of mayflies in maintaining the balance of various ecosystems.

Here are some key characteristics of mayflies:

  • Short adult life span, often less than 24 hours
  • Unique life cycle featuring a subimago stage
  • Four membranous wings with front pair often longer than hind pair
  • Two long, threadlike appendages extending from the tip of abdomen

Mayflies also have an impact on human culture. They inspire artists such as musicians, poets, and writers. Interestingly, they are even the namesakes of various water and aircraft, as well as the focus of festivals celebrated worldwide.

In summary, mayflies play a crucial role in preserving our environment and contributing to human culture. Your awareness and appreciation of their importance to our world help contribute to their conservation efforts. So, next time you encounter these fascinating insects, remember the unique position they hold in our ecosystem.

Diet of Mayflies

Mayflies are an important part of many ecosystems due to their role in the food chain. As nymphs, mayflies primarily consume organic matter, detritus, algae, and living plants. Their diet classifies them as herbivores, and they play a crucial role in nutrient cycling in aquatic environments. For example, by consuming algae, they help keep the growth of this plant in check.

In turn, mayflies are a key food source for many animals higher up in the food chain. Both in their nymph phase and as adults, they are preyed upon by various predators like:

  • Fish
  • Birds
  • Spiders
  • Frogs

A comparison between mayflies and grasshoppers in terms of their diet shows some similarities:

Mayflies Grasshoppers
Diet Algae, detritus Grass, plants
Predators Fish, birds, spiders Birds, mammals
Role in Ecosystem Nutrient cycling, food source Herbivores, control plant growth

Keep in mind that the specific diet of a mayfly can vary depending on its species and living environment. Overall, it’s clear that understanding the diet of mayflies and their role in the ecosystem is important for maintaining healthy and balanced aquatic environments.

Enjoy exploring more about these fascinating insects and their impact on the world around you!

Other Aquatic Insects

Besides mayflies, there are several other aquatic insects that play essential roles in aquatic ecosystems. Let’s take a look at some of them.

Water Beetles are an essential food source for many aquatic animals such as fish and birds. They are predators and help control other insect populations in the water. Some common types of water beetles include:

  • Diving beetles
  • Whirligig beetles
  • Water scavenger beetles

Caddisfly larvae are often found in streams and rivers as they prefer flowing water. They play a crucial role in breaking down organic matter from plant debris, which helps recycle nutrients back into the ecosystem. Caddisfly larvae are also an essential food source for fish and other predators.

When comparing mayflies to caddisfly larvae and water beetles, some similarities and differences include:

Insect Type Similarities Differences
Mayflies All insects are aquatic and are food sources Prefer still water habitats
Caddisfly Larvae for fish and other predators in the ecosystem Prefer flowing water habitats
Water Beetles Predators, unlike mayflies and
caddisfly larvae

In conclusion, there are many fascinating aquatic insects like mayflies, water beetles, and caddisfly larvae. Each has unique characteristics and plays an essential role in maintaining balanced aquatic ecosystems. So next time you’re near a body of water, keep an eye out for these tiny yet crucial inhabitants.

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 – Giant Mayfly


six legs, wings, body similar to dragon fly
February 18, 2010
While fishing in Canada last summer, we woke up one morning to find these creatures completly covering our boat and dock. I took a picture of one of them, because they just suddenly appeared one morning, and I didn’t see them after that.
I took a picture of this flying creature while fishing at Eagle Lake in Ontario CA, and I’m curious at to what it might be.
Daniel F
Eagle Lake-Ontario Canada


Hi Daniel,
This is a Mayfly in the order Ephemeroptera, and we believe it is Hexagenia limbata, a Giant Mayfly, based on images posted to BugGuide.  Adult Mayflies do not feed, and they live long enough to mate and die, often providing food for fish and birds when they appear in astronomical numbers.  The name for the order has its root in the Greek word “ephemeros” which refers to the adults living for a single day.  Your observation is consistent with the life cycle of this awesome insect.  As an angler, you should be aware that many fishing lures are patterned after Mayflies.  You might also consider using Mayflies as live bait, especially after reading this post from our website.

Letter 2 – Golden Mayfly


Subject: yellow bugs in kansas lake bathrooms
Location: kansas
August 2, 2012 5:28 am
They climb on walls and fly. They act a lot like moths but are very easy to catch.
Signature: amber

Golden Mayfly

Hi Amber,
This insect is a Mayfly in the insect order Ephemeroptera.  We believe based on its size and color, it is a Golden Mayfly in the genus
Hexagenia, and it might also be called a Giant Mayfly or a Burrowing Mayfly.  According to BugGuide they are:  “Very large mayflies. Usually pale golden yellow at least when freshly emerged, i.e., subimago.”  BugGuide also notes:  “Adults emerge in evening, disperse widely, coming to lights–often far from bodies of water.”  The proximity of the bathrooms to the lakes and the lights at night are solid reasons why these Golden Mayflies are congregating at the bathrooms.  This individual is a subimago.  Mayflies are the only insects known to molt while in the winged form, and the initial molt from nymph to winged adult is called the subimago.  A second molt occurs soon after and the Mayfly is in its fully adult, reproductive form.

Letter 3 – Flatheaded Mayfly, we believe


Subject: What type of Mayfly is this?
Location: Columbia, MO
April 29, 2013 5:17 pm
A fly fishing buddy and I are trying to identify the name of this mayfly. Any help would be appreciated. I took this picture on my back porch in Columbia, MO on 4/29/13 at 7pm.
Signature: DocChad

Possibly Flatheaded Mayfly

Hi DocChad,
We tend to be amateur generalists here at What’s That Bug? and we are not very good at keying out difficult species.  With that said, this Mayfly appears to be very similar to this image posted to BugGuide that is identified as being in the family Heptageniidae, the Flatheaded Mayflies.

Flatheaded Mayfly, we believe.
Flatheaded Mayfly, we believe.

Letter 4 – Giant Mayflies


Thanks, Daniel! I really enjoy spending time on your site. You have put together an incredible resource. My curiosity causes me to want to identify every bug I see that I am not familiar with. As a fly-fisherman and fly-tier, that curiosity has grown as I have many opportunities to view and identify species around the streams and lakes. Attached is a picture that I took at a northwest lake of a couple of Hexagenia Limbata Mayflies. The Hexagenia Limbata is the second largest species of mayfly. While these are more commonly found in Eastern states like Michigan and Wisconsin, there are a very few isolated rivers and lakes in the West where they hatch abundantly. The experience of being on a lake during a "Hex" hatch is incredible! The mayflies look like hundreds of miniature helicopters rising from the water all around you! And the fish loose all sensibilities (sorry, anthropomorphizing) and go nuts trying to get them!

Dear TroutCast,
Your personal observations and comments and excellent photo of Giant Mayflies, Hexagenia limbata, are exactly the type of submission we love posting to our site. What a welcome addition. We also found a great site called Troutnut.com to link to regaring additional information on the Giant Mayfly.

Letter 5 – Golden Mayfly


Subject: What’s this winged insect?
Location: Southern Idaho. (Irrigated land)
January 30, 2014 12:52 pm
I snapped a few photos of this insect with upright laced type wings. Then I posted the photo on FB. Of course the first question was, ” What is it?” I searched the internet to no avail other than I believe that it is in the family Neuroptera. Can you help me identify it?
Signature: Puzzlebug


Dear Puzzlebug,
First off, Neuroptera is an order, a broader classification than a family.  Your Mayfly is in the order Ephemeroptera, which  according to BugGuide, originates from the: “Greek ephemeros ‘of/for a day; short-lived’ + pteron ‘wing’ — refers to the short-lived adults [‘ephemeros’ comes from epi ‘upon’ + hemera ‘day’].”  Your individual is in the genus Hexagenia, and the common names are “Burrowing Mayfly, Giant Mayfly, Golden Mayfly”
according to BugGuide.  Mayflies are unique in that the adults or imago undergoes two molts.  The larvae of a Mayfly is aquatic and is known as a nymph or a naiad.  Upon reaching maturity, it leaves the water and molts, emerging as a winged pre-adult or subimago.  Shortly afterward, it molts a second time, emerging as a full adult or imago.  These Giant Mayflies are also prized bait for anglers who fly fish.  According to BugGuide, the anglers even distinguish between the subimago that has “wings cloudy in appearance, body dull and pubescent, with appendages somewhat shorter — but otherwise similar to imago” of a Mayfly which they call a dun and an adult that is called a spinner which has “wings usually transparent but sometimes patterned, held vertically and together above thorax when at rest”.  Since the wings appear cloudy, we believe this is a subimago.  Compare your individual to this image on BugGuide.  The position of the body of your Golden Mayfly conforms to BugGuide’s description:  “front legs often held forward and sometimes upward in front of head when at rest.”  Because of your northern location, we are speculating that this Golden Mayfly is Hexagenia limbata and you might enjoy reading more about it on TroutNut.  We are going to contact Eric Eaton to see if he can provide any additional information.

Hi Eric,
This giant mayfly is from southern Idaho, so I am guessing Hexagenia limbata, but BugGuide’s descriptions have me a bit confused.  The wings appear cloudy, so I would guess subimago, but the front legs are held in the position BugGuide indicates is used by the imago.  So, which is it?  Imago or subimago?  I lean subimago

Eric Eaton Responds
I am not an expert on aquatic insects *at all,* so I’m hesitant to make a definitive statement.  I agree with the genus-level ID at the least.
It might be a subimago, especially if there is no shed exoskeleton close by.  Otherwise, it could be a freshly-molted imago.  The subimago emerges from the nymphal exoskeleton right on the water or very close by.  The imago emerges later, usually on vegetation, often some distance from water.

Thanks Eric,
Often we are asked to identify the exuviae of Mayflies, and when they are on the sides of homes, they definitely were left by the subimago after the final molt.

Letter 6 – Gray Fishfly


Bug ID
June 28, 2010
This bug was near our front entrance on our home. We found it curious enough to snap a few pics. My wife and I have never seen one like this in our region and we have both lived in this rural home for nearly 20 years. I grew up very nearby and it is my curiosity that makes me wonder why it is here.
Any assitance appreciated.
Curt in California
Nothern California

Gray Fishfly

Hi Curt,
Your visitor is a Gray Fishfly in the genus Neohermes, probably Neohermes californica.  That species is commonly called a California Dobsonfly.  You can read a bit more on BugGuide.  This should be a local insect for you.

Letter 7 – Male and Female Fishfly in Virginia


Subject: Male and Female Fish Fly?
Location: Troy, VA
June 30, 2016 2:25 pm
I believe these are male and female fish flies. The female was very active while the male just sat there. I don’t think she ever closed her wings. I will draw no conclusions from this.
Signature: Grace Pedalino

Male Fishfly (Pectinate Antennae)
Male Fishfly (Pectinate Antennae)

Dear Grace,
We really love your newest images.  Perhaps you captured these Fishflies post-coital and he has completed his mission and now can contribute to the food chain, while she must have the energy to lay eggs in a nearby aquatic environment.  It is late in the season for Spring Fishflies, according to BugGuide, but your female appears to have serrate or saw-like antennae, a characteristic of the female Spring Fishfly as opposed to the female Summer Fishfly, though this is the season for the Summer Fishfly according to BugGuide, as both female and male Summer Fishflies have pectinate or comb-like antennae, along with only the male Spring Fishfly.  Read more about the Spring Fishfly,
Chauliodes rastricornis, on BugGuide and also read more about the Summer Fishfly, Chauliodes pectinicornis, on BugGuide.  It took us years finally to get images of mating, related Dobsonflies. We prefer your image of the male Fishfly on the white background as it better sets off his antennae.

Female Fishfly (Filiform Antennae)
Female Fishfly (Serrate Antennae)

Letter 8 – Male Fishfly


Subject: Big flying bug on porch
Location: Mentor,ohio
May 31, 2016 4:22 pm
Hi ! Is anyone able to identify this bug? Thanks! He was on my porch,has big wings, and I think is hurt so please answer asap!
Signature: From

Male Spring Fishfly
Male Spring Fishfly

This is the third image of a Male Spring Fishfly we have posted this week.


  • 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.

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  • 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.

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4 thoughts on “Exploring the Natural Predators of Mayflies”

  1. Mayflies: consumed, yet not amazingly popular…

    There’s a history of mayfly consumption in Papua New Guinea (species unknown, I think). But that’s the only example I know of, except for the occasional adventurous fisherman who wants to start thinking like a fish. Yet here are numerous examples of mass emergences; if I were present during one of those, I’d have a hearty meal of them.


  2. Thank you, glad you like them. There is a small stream and small lake nearby, so I guess that’s where she has gone. I never seem to see the same bugs two days in a row. There was cooler than usual weather for a while this spring, perhaps that’s why these two are off schedule. Please let me know if I ever send too many photos. Thanks for the information.


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