Where Do Mayflies Live: Unraveling the Mystery of Their Habitat

Mayflies are fascinating insects that are often associated with the arrival of summer. They can be found in various habitats, but one thing is common among all species – these delicate creatures have a strong connection to water. As you learn more about mayflies, you’ll discover their intriguing life cycle and the specific conditions they need to thrive.

During their short lives, mayflies are primarily located near bodies of freshwater, such as rivers, lakes, and streams. These insects play a vital role in the ecosystem, serving as a primary food source for fish and other aquatic animals. Their presence also serves as an indicator of water quality, with larger numbers of mayflies typically hatching in cleaner waters.

Now that you have an idea of where mayflies live, exploring their habitats further can provide insightful information about their life cycle, behavior, and contribution to the environment. So, whether you’re an avid nature enthusiast or just curious, understanding the world of mayflies can be both gratifying and educational.

What are Mayflies?

Mayflies, also known as Ephemeroptera, are a group of insects that belong to the order Ephemeroptera. They are commonly known for their short-lived adult stage, which lasts anywhere from a few hours to a day or two. Here’s a brief overview of mayflies and their unique characteristics:

Mayflies are aquatic insects in their larval stage, living in various freshwater habitats, such as streams, ponds, and lakes.
The adult mayflies are delicate creatures with large compound eyes, short antennae, and two long, threadlike cerci (antenna-like appendages) extending from their abdomen.
They possess four membranous wings, with the forewings being much longer and overlapping the hindwings.

Adult mayflies are mainly seen during their mating swarms, which is when they are most commonly noticed by humans. Not sure how to recognize them? Here are some typical features of adult mayflies:

Slender, soft-bodied appearance.
Wings held upright and together, similar to a butterfly.
Front pair of legs often held outward when perching.

Ephemeroptera is an ancient group of insects that has been around for millions of years. They share some common traits with other types of flies but have evolved separately from them. So, while mayflies might resemble some other flies in appearance, they can easily be distinguished by their unique characteristics and life cycle.

Remember, the next time you see these delicate insects swarming near a body of water, you’re witnessing the fascinating world of mayflies and their ephemeral existence!

Anatomy of a Mayfly

When observing a mayfly, you’ll notice its slender, soft body and four membranous wings. These wings are extensively veined and held upright together, somewhat like a butterfly’s wings. The forewings are much longer and often overlap the hindwings. They come in various sizes, depending on the species ¹.

Concerning the legs, mayflies have three pairs, with the front pair often held outward while perching. The legs are quite delicate, and they serve primarily for perching and not for walking. Their mouthparts are designed for feeding on algae and other organic materials.

Mayflies have short antennae and large compound eyes, which are especially bigger in males to help them locate females for mating. You’ll also find two long, threadlike tails (cerci) extending from the tip of the abdomen ¹. These cerci help mayflies maintain balance when they are in motion.

Using this information about their wings, abdomen, antennae, eyes, tails, legs, mouthparts, and thorax, you can easily identify and recognize mayflies in their natural habitats. Keep an eye out for these fascinating insects, which are a testament to the variety and complexity of the insect world.

Life Cycle of Mayflies

The life cycle of mayflies is unique among insects as it includes a subimago stage. Let’s explore their life cycle in detail.

Eggs: Female mayflies lay between 500 to 3,000 eggs on water surfaces. Depending on the species, it takes a few days to several weeks for eggs to hatch.

Nymphs/Larvae: After hatching, nymphs (or larvae) emerge, spending their time underwater. Some nymphs are fast swimmers, like the Baetis, while others, like the Isonychia, are filter-feeders. Nymphs molt multiple times during this stage.

Live underwater for months to a year
Occupy various freshwater habitats
Have gills for breathing
Multivoltine species may have several generations per year

Subimago: As they transition to their adult stage, mayflies have a short-lived subimago stage, during which they are mobile. This stage typically lasts about 24 hours, and they molt once more.

Imago/Adult Stage: Mayflies are weak flyers with delicate wings, large compound eyes, and long, threadlike cerci. They are characterized by their membranous, overlapping wings. Mating and egg-laying occur during this stage.

Unfortunately for mayflies, their adult lifespan is quite short, ranging from just a few hours to a couple of days.

In summary, the life cycle of mayflies involves eggs, nymphs, subimago, and imago stages. They are known for their incredibly short adult lifespan and unique subimago stage, setting them apart from other insects. This life cycle allows them to thrive in various freshwater environments, contributing significantly to the ecosystem.

Reproductive Behavior

You may find it fascinating that mayflies have a unique reproductive behavior. These insects form swarms and engage in aerial mating displays to find a suitable partner.

Male mayflies gather in groups to attract female mayflies. Once they pair up, the mating process begins. During mating, the male clasps the female from above and deposits sperm. After fertilization, the female lays her eggs in a nearby water body.

Mayflies have a short life span, so their reproductive process is often quite rapid.
Males die shortly after mating, while females usually pass away after laying eggs.

Here are some noteworthy points about mayfly reproductive behavior:

Swarms: Males gather in large groups to attract females.
Mating: Males and females mate in mid-air, with the male clasping the female from above.
Reproduction: The female lays her eggs in water after fertilization, and both adult mayflies die shortly after.

Now that you know more about the reproductive behavior of mayflies, you can appreciate how these fascinating little creatures engage in their brief, yet productive lifecycle.

Where Do Mayflies Live

In your quest to learn about mayflies, understanding their habitat is essential. Mayflies can be found in various water bodies across the world, particularly in North America. They primarily reside in freshwater environments such as streams, rivers, ponds, and lakes.

You might be wondering how they adapt to different ecosystems. Let’s briefly explore some common mayfly habitats:

Streams and rivers: In these flowing water bodies, mayflies can thrive as bottom-dwelling insects. These habitats are often abundant with mayflies, indicating good water quality and a healthy ecosystem.
Ponds and shallow lake areas: Mayfly nymphs also inhabit calm and heavily vegetated waters found in ponds and shallow parts of lakes. They can serve as an essential food source for other aquatic animals.

Now, let’s look at some specific species and their preferred habitats:

Baetidae: Often found in fast-flowing water, these mayflies are agile swimmers and fusiform in shape.
Heptageniidae: Commonly known as flat mayflies, this family prefers slow, sandy or rocky streams.
Oligoneuriidae: As filter-feeders, the Isonychia species is drawn to streams with a moderate flow.
Leptophlebiidae: Paraleptophlebia, another species of mayflies, is typically found in small streams.

In conclusion, mayflies are versatile creatures that play a vital role in the ecosystems they inhabit. By understanding their various habitats, you can better appreciate their contribution to the aquatic world.

Mayflies and the Ecosystem

Mayflies play a crucial role in maintaining the balance of freshwater ecosystems. These small, diverse insects are associated with liquid freshwater environments across the globe ^(1)^. Let’s explore how they interact with various inhabitants of the ecosystem.

Algae and Plants

As aquatic nymphs, mayflies primarily feed on algae and plant material. Their grazing can help control the buildup of algae in freshwater systems.

Fish and Birds

Mayflies serve as an essential food source for fish like trout, birds, and other animals, especially during their emergence periods. When these hatch events occur, predators such as frogs, beetles, and bats can be seen feasting on them.

Role in Ecosystem

Mayflies are an important indicator of water quality. Healthy mayfly populations signify good water quality ^(5)^.
They contribute to nutrient cycling by breaking down plant material and recycling dead organisms.
As they metamorphose and emerge as adult mayflies, they provide a valuable energy source for:
- Fish (e.g., trout)
- Birds
- Aquatic insects
- Invertebrates
- Reptiles

Summary Table

Mayfly Life Stage	Effect on Ecosystem	Examples
Nymph (aquatic)	Feed on algae & plants	Improve water quality, algae control
Adult (terrestrial)	Serve as prey for predators	Food for fish, birds, and other animals

So, as you can see, mayflies and their life stages impact a wide variety of ecosystem components, serving various functions to help maintain the delicate balance of life within freshwater environments.

Mayflies and Fly Fishing

Mayflies, also known as shadflies, dayflies, or drakes, are a group of aquatic insects that provide various benefits to the ecosystem. Adult mayflies typically live near water sources and can be found in a wide range of habitats, such as rivers, streams, and lakes. Fly fishers often use mayfly patterns to mimic the insect’s life stages when fishing.

As a fly fisher, you may already know that mayflies are an essential part of the aquatic food chain. Their nymph stage, when they have gills and live underwater, serves as an important food source for many animals, especially fish like trout and bass. This makes them an ideal target for fly anglers who want to maximize their catches.

Mayflies’ appearance and life cycle make them an attractive choice for creating fly patterns. The adult mayfly has four membranous, veined wings, held upright, giving them a distinctive look. They also have two long, threadlike cerci, which are antenna-like appendages extending from their tail end. Mimicking these features with feathers and other materials can create realistic imitations to attract fish.

Some key factors to consider when fly fishing with mayfly patterns include:

Fly Species: Be aware of the specific mayfly species present in the water body you’re fishing in, as this can affect the appearance and behavior of the nymphs and adults.
Life Stage: Adult mayflies emerge from the water in different stages, including the subimago stage and the final imago stage. Choose your fly patterns according to the stage you want to mimic.
Time of Day: Mayflies typically hatch during specific times of the day, so adjust your fly selection and fishing techniques accordingly.

Fly fishing with mayfly patterns can be a rewarding and enjoyable experience for anglers of all skill levels. By understanding the intricacies of these fascinating insects and incorporating them into your fly tying and fishing strategies, you can increase your chances of success on the water.

Mayflies and Water Health

Mayflies are delicate insects that live near freshwater sources, such as rivers, lakes, and streams. These insects are highly sensitive to their environment, making them excellent indicators of water quality. Generally, mayflies thrive in clean water habitats with low pollution levels.

When you find mayflies near a body of water, it indicates that the water is in good condition, free from harmful pollutants. Mayflies are intolerant to water pollution, so their presence demonstrates that the water is clean and has a well-balanced ecosystem supporting a range of flora and fauna. In contrast, if mayflies are absent or scarce, it suggests water quality issues that might require attention.

A few main factors impact water quality where mayflies reside:

Nutrient levels: An abundance of nutrients, such as nitrogen and phosphorous, can promote algal blooms. These blooms deplete oxygen levels, making it difficult for mayflies and other aquatic species to survive.
Pollutants: Harmful substances, such as chemicals, heavy metals, and organic matter, affect water quality and mayflies’ delicate physiology.
Water temperature: Changes in water temperature can affect mayflies’ growth, reproduction, and survival rates. Warmer waters often carry more pollutants and dissolved oxygen, leading to a decline in mayfly populations.

There are several ways to help protect and conserve the habitats where mayflies live:

Keep pollutants, such as chemicals and litter, out of water sources.
Implement buffer strips along waterways to filter out pollutants.
Engage in proper waste disposal practices to prevent contaminants from entering the water.

By ensuring the water quality remains high, not only do we support mayfly populations but also contribute to overall aquatic ecosystem health. Remember, the presence of mayflies signifies clean water and a thriving environment for all living organisms.

Facts about Mayflies

Mayflies are unique aquatic insects with a fascinating life cycle. They can be found near various bodies of water, such as rivers and streams. Let’s take a closer look at some of their features.

Appearance: Mayflies have a slender, soft body with large compound eyes and short antennae. They have four veined wings held upright and together, resembling a butterfly. Their size can vary, with length ranging from 3 to 30 millimeters.

Diet: Mayflies typically feed on detritus, organic matter found in water. They play an essential role in nutrient cycling, breaking down these materials and providing a vital source of protein for fish and other water-dwelling creatures.

Life Cycle: Mayflies have a unique life cycle that includes a larval, subimago, and adult stage. The subimago stage is an active, mobile phase between the larval and adult stages. The duration of their life cycle can range from a few months to several years, depending on the species.

Types: There are several different types of mayflies, with around 3,000 known species worldwide. In North America, some common examples include Baetis, Stenonema, and Paraleptophlebia.

Species	Habitat	Size
Baetis	Rivers, streams	Small, 5-10 mm
Stenonema	Rivers, streams	Medium, 10-20 mm
Paraleptophlebia	Small streams	Small, 3-10 mm

Evolution: Mayflies have evolved over millions of years and are considered one of the most ancient groups of insects. Their fragile, ephemeral nature symbolizes the fleeting beauty of life.

Now that you have a general understanding of mayflies, you’ll be able to appreciate their role in the ecosystem and the delicate balance created by their intriguing life cycle.

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 – Bug of the Month June 2019: Mayfly with white eyes

Subject: White Eyed Bug
Geographic location of the bug: Bernville, Pennsylvania
Date: 05/27/2019
Time: 06:27 AM EDT
Your letter to the bugman: I found this sitting on the door frame of my patio door. I am trying to identify it, and hoping you might be able to help.
How you want your letter signed: Troy

Dear Troy,
This unusual creature is a Mayfly in the insect order Ephemeroptera. This BugGuide image and this BugGuide image of individuals in the genus Maccaffertium closely match your specimen. Mayflies are unusual in the insect world in that their final molt is divided into two phases, the first being called the subimago, and though it is winged, it is not fully mature. A second molting that usually occurs within a few days produces the mature adult. We are uncertain why the eyes on your individual and on some of the images posted to BugGuide are white. Your images are beautiful. Though it is a few days before the beginning of June, we have decided to post your submission as the Bug of the Month for June 2019. We hope someone can clarify why the eyes on some Mayflies are white. Our suspicion is that this is a newly molted individual and that the eyes will eventually darken.

Letter 2 – Mayfly from Newfoundland

Subject: Strange bug
Location: Newfoundland
August 18, 2015 5:12 pm
I live in Trepassey Newfoundland, Canada. I saw an odd bug today at work that I’ve never seen before in my entire life, but today I saw three! Could you possibly identify it?
Signature: Tyler Ryan

Dear Tyler,
This is a Mayfly in the insect order Ephemeroptera.

Letter 3 – Dark Fish Fly

Looks like a Fish Fly
July 20, 2009
Hello bugman. I have briefly looked at your dobson fly and fish fly images and am leaning towards the fish fly for the specimen (of many around my home) that I have photographed. Although this one is missing one of his antennae, the remaining antennae somewhat reveals the absence of the feather like protrusions on one side which is said to be one of the defining characteristics of the Fish Fly. As well, the absence of any distinctive mandibles seems to discredit the possibility of a Dobson Fly. Sooo, did one of these critters from each family get together one night and have a party, and this is the result?
thanks for any info.
Shrew
Nova Scotia, Canada

Hi Shrew,
This is a Fish Fly, more specifically, a Dark Fish Fly, in the genus Nigronia which we located on BugGuide. Dobsonflies, Fishflies and Dark Fishflies are in the same family, Corydalidae, but in different genera. This is how BugGuide identifies the differences between the two species: “Wings with large white areas more or less continuous, especially across the middle; anal area of hindwing white; male antennae modified pectinate; female antennae serrate—Nigronia fasciatus Wings with white spots isolated often associated with crossveins; anal area of hindwing brown; male and female antennae serrate— Nigronia serricornis“. We would lean more towards Nigronia serricornis. This is the first Dark Fish Fly we have received and we are thrilled to add it to our archives.

Letter 4 – Mayfly from the UK

Subject: Damselfly?
Location: Nottingham, UK
June 4, 2017 6:56 am
Pic taken in Nottingham, UK, June 2017
Signature: Gerold Baier

Dear Gerold,
Your image is beautiful. This is NOT a Damselfly. It is a Mayfly in the order Ephemeroptera. We found a perfect match to your individual on Wildlife Trust, but alas, it is not identified to the species level, though the site does state: “There are 51 species of mayfly in Britain. They are common around freshwater wetlands, from fast-flowing rivers to still lakes, where the larvae spend their lives underwater feeding on algae and plants. The adults hatch out, usually in the summer, and have very short lives (just hours in some cases) during which they display and breed; hatchings of hundreds of adult mayflies in the same spot at the same time often occur. Many species do not feed as adults as their sole purpose is to reproduce and once they have mated, they die. The common name is misleading as many mayflies can be seen all year-round, although one species does emerge in synchrony with the blooming of Hawthorn (or ‘Mayflower’).” We believe we have identified your species as Ephemera vulgata thanks to BugLife which states: “Mayflies are unique as insects in having two winged adult stages. After emerging from the water they fly to the bank where they shelter on the underside of leaves or in the grass. They then moult again, leaving behind their drab ‘dun’ skin to reveal their shiny ‘spinner’ skin. Following this moult they fly back to the water and form mating swarms dancing above the surface.” We are post-dating your submission to go live to our site later in the month while our editorial staff is away on holiday.

Fascinating! Thank you for the reply

I need to correct the data on the photograph: it was taken on 2nd June 2017 on the banks of the Derwent River in Rowsley, Derbyshire, UK

postcode DE4 2EB.

The mayfly is sitting on a red car. I attach another image where the reflection is nice.

Gerold

Letter 5 – Mayfly Exuvia from Australia

Subject: Transparent insect
Location: Australia, Melbourne
March 10, 2016 4:38 pm
Hi, I saw this fella as I was leaving the house for work this morning. Didn’t have a lot of time to stand around so I took a quick snapshot and left. It didn’t move once. I estimate it’s between 1-2cm in total length.
Signature: K

Dear K,
The insect, most likely a Mayfly, has flown away, leaving behind this exuvia, or cast off exoskeleton. Since Mayfly larvae are aquatic, we are guessing you live near water.

Hi,
Sorry a little late seeing this reply. Thank you for taking the time!
Actually I live in the suburbs but the closest river is about 3 km away so I guess it’s not surprising. This is the first time I’ve seen one though and figured it wasn’t alive when it stayed there for about a week lol.
Thanks again!

Letter 6 – California Fishfly

Subject: Some sort of antlion?
Geographic location of the bug: Northern California
Date: 07/24/2019
Time: 12:27 PM EDT
Your letter to the bugman: Hello there! My dad was watering our plants outside and I guess managed to (accidentally!) shoot this guy right out of the air. He’s certainly had his bell rung, I’m taking care of him and hoping to let him go soon 🙂 But I’d like to know what he is as I’ve never seen anything like this creature before, and he’s BIG! I managed to find something called an “antlion” which he looks most like. Is that correct?
How you want your letter signed: McKinley

Dear McKinley,
This is not an Antlion. It looks to us like a California Fishfly or Western Dobsonfly, Neohermes californicus, which is pictured on BugGuide. According to BugGuide: “appear to prefer streams (Chauliodes prefer still water)”

Letter 7 – Common Burrower Mayfly

Unknown Texas Flying Horned Beauty
August 10, 2009
Dear Bugman:
I was camping at the Guadalupe River in South Texas when I noticed this little guy attached to our bench. What is it?
Jen
New Braunfels, Texas

Hi Jen,
This is a Mayfly in the order Ephemeroptera. We are a bit intimidated to attempt actual species identification of Mayflies, but we do believe your individual is in the family Ephemeridae, the Common Burrower Mayflies as illustrated on BugGuide. If we were to take a stab at a species, we believe this may be Hexagenia limbata which is described on BugGuide. What you are calling horns are actually the front legs, and this posture is quite typical of Mayflies at rest.

Thank you! I love your site and you are amazing!

Letter 8 – Common Burrower Mayfly

Is this a moth? A butterfly? A beetle? Identification please!
October 23, 2009
Hi, I’m a photographer and one day out on my porch I saw this bug. I just had to take pictures of it, but I was completely dumbfounded as to what type of insect it was. The picture was taken early this past summer and I’ve been searching for identification ever since. It’d be great if you guys could tell me what it is so I can finally label it in my portfolio!
Thanks so much!!! Clair Jones
Northern Virginia

Hi Clair,
Your insect is none of the above. It is a Mayfly, a group of ephemeral insects that only lives in the adult form for a few days, long enough to mate. Though they often appear in great numbers in the month of May, they can be found at other times as well. This appears to be a Common Burrower Mayfly in the family Ephemeridae, based on images posted to BugGuide.

Letter 9 – Dark Fishfly

Subject: ID Please
Location: Western MA, USA
March 27, 2016 7:09 am
Hi,
I have looked around quite a bit & keep coming up empty handed. For some reason I got “doodlebug” stuck in my head, however that does not seem correct.
It was having issues navigating climbing the stalks & leaves of the low-lying, plants that were stream side. I am not sure if it had just emerged or had some fermented fruit….
Taken 6/3/15 – Holyoke, MA – At a reservoir. I have not seen one since….
Thank you….
Signature: Kristi

Dear Kristi,
Your Dark Fishfly in the genus Nigronia is only represented on our site with a two postings so we are thrilled with your submission and your excellent quality images. Based on BugGuide images, we believe your individual is Nigronia fasciata. According to BugGuide: “Emergence of adults may be synchronized. Adults are diurnal (seen flying near streams) and also nocturnal, so come to lights. Eggs are laid on the underside of vegetation overhanging a stream. Larvae are aquatic, predatory. Perhaps take three years to mature in more temperate areas, such as West Virginia. Pupation occurs in earthen cells on the edge of streams.” It is possible that the flight time in various locations is so brief that if one is not looking at that time, it could be years between sightings.

Letter 10 – Dark Fishfly

Subject: Weird butterfly creature
Geographic location of the bug: Kingston Ontario Canada
Date: 02/08/2018
Time: 05:35 PM EDT
Your letter to the bugman: This weird bug was hanging around my dock in June. It had a very long body, and was pretty clumsy when it flew. It looked as though its body was to heavy to support it. It hung out in the cedars for a long time and then disappeared. I have tried to figure out what it is through google, a bug book and friends and no one has a clue! Hoping you can help!
How you want your letter signed: Martha

Dear Martha,
This is not a butterfly. It is a Dark Fishfly in the genus Nigronia which is pictured on BugGuide where it states: “Emergence of adults may be synchronized. Adults are diurnal (seen flying near streams) and also nocturnal, so come to lights. Eggs are laid on the underside of vegetation overhanging a stream. Larvae are aquatic, predatory. Perhaps take three years to mature in more temperate areas, such as West Virginia. Pupation occurs in earthen cells on the edge of streams.”

Letter 11 – Dark Fishfly Ovipositing

Subject: what’s this insect
Location: western Maryland
May 27, 2015 7:07 am
Wondering if this was another type of Dobson fly. was laying eggs in clumps on leaves beside the river. North branch Potomac river.
Signature: jordan

Hi Jordan,
Your Dark Fishfly in the genus Nigronia is classified in the same order as a Dobsonfly. We believe your individual is Nigronia fasciata based on comparing the markings on the wings to individuals posted to BugGuide. According to BugGuide: “Emergence of adults may be synchronized. Adults are diurnal (seen flying near streams) and also nocturnal, so come to lights. Eggs are laid on the underside of vegetation overhanging a stream. Larvae are aquatic, predatory. Perhaps take three years to mature in more temperate areas, such as West Virginia. Pupation occurs in earthen cells on the edge of streams.”

Letter 12 – Dark Fishfly Ovipositing

Subject: Dobsonfly laying eggs
Location: Southwestern Maine
April 5, 2016 4:46 am
Dear Bugman,
This photo was taken last year at a river in Maine. Our family is fascinated by all creatures, great and small. So I was thrilled to be lucky enough to come across this Mama laying her eggs.
Signature: The Cartwrights, NH

Dear Cartwrights,
Your images are awesome, however we need to make a slight correction. This is not a Dobsonfly. This is a closely related Dark Fishfly in the genus Nigronia. According to BugGuide: “Emergence of adults may be synchronized. Adults are diurnal (seen flying near streams) and also nocturnal, so come to lights. Eggs are laid on the underside of vegetation overhanging a stream. Larvae are aquatic, predatory. Perhaps take three years to mature in more temperate areas, such as West Virginia. Pupation occurs in earthen cells on the edge of streams.” Your images illustrate an option to laying eggs on vegetation.

And we learned something new! Thank you so much 🙂

Letter 13 – Exuvia of a Mayfly

Unknown Bug! mars o shrimp!
Location: middle east
October 17, 2011 5:05 am
Hi there,
you guys are amazing.i’m so glad that ive found you.last week i was hanging around in my house that suddenly i saw a bug.i have no idea what is it,hope you can identify it.
Signature: MD

mayfly_exuvia_middle_east — Exuvia of a Mayfly

Dear MD,
This is the exuvia or shed exoskeleton of a Mayfly. The aquatic nymphs of Mayflies, known as naiads, leave the water to molt into winged subadults, and what you found is the remain of the molting process. See this image from BugGuide that looks similar.

Letter 14 – Mayfly from Portugal

Subject: Identify bug
Location: Coimbra, Portugal
April 12, 2014 9:01 am
Hi,
I’m from Portugal, and I live in a village where you can find a lot of this kind of bug. Usually they’re in windows or walls, and they barely move. Sometimes I see one and in the next day it is in the same exact place. They look like they have wings but I never saw it fly, even when you lightly touch them. But they move! They look like they have two really big needles (but thin) on the bottom but they look inoffensive.
Signature: David

Hi David,
This is a Mayfly in the order Ephemeroptera, and winged adults do not eat and only live a few days, long enough to mate and reproduce. Larval nymphs are aquatic and they are known as naiads. Since adults are weak fliers, they are generally found near the water source that spawned them, so we expect there is a sluggish stream or pond nearby. The threadlike tails or cerci are not harmful. See Encyclopedia Britannica for more information on Mayflies.

Yes, there is a water source nearby. Thank you for your answer! Keep up the good work!

Letter 15 – Mayfly from the UK

weird insect!
Location: Paddington, London, UK
August 10, 2011 5:20 am
hi there,
I have seen this couple of times in the gents toilet and wonder what that thing really is!!
Signature: any way possible

Dear any way possible,
This is a Mayfly in the order Ephemeroptera. Mayflies are fascinating insects that have aquatic larvae. Sometimes adults are so plentiful the pavement under street lights becomes slick with their smashed bodies. Mayflies are an important food source for fish, birds, insects and other insectivores.

Letter 16 – Bug of the Month April 2016: Spring Fishfly in North Carolina

Subject: Unusual moth
Location: Central north carolina
March 30, 2016 9:19 pm
Hi! Last night this guy flew into my house to hang around on the wall near a lamp. I hadn’t seen this kind of bug before so I isolated it under a glass before letting it back outside. It would be nice to know what species it is and if it’s the male or female of said species. I’m only guessing moth by the antennae. Here is what I’ve observed: with wings closed its about 1.5-2 inches long, 6 legs, narrow when wings are closed wings start fairly far away from the eye region, Fuzzy moth like antennae, 2 sets of wings, body is very slender, smooth, and long when wings are open. Almost like how a dragon fly is situated. Either vey dark brown or black in color all over. Wings have a same color raised textured on them. Sorry the pictures aren’t the best. And I am unsure of the wing span.
Signature: Thanks! Lauren

Dear Lauren,
This is a male Spring Fishfly, Chauliodes rastricornis, and here is what BugGuide has to say: “Compare C. pectinicornis. Head and pronotum have dark markings on light brown background, as opposed to yellowish markings on dark brown background of C. pectinicornis. Antennae of female serrate, of male, pectinate. So, apparently, a Chauliodes with serrate antennae should be a female C. rastricornis. Note earlier flight (spring) of rastricornis in most of east. C. pectinicornis typically flies in summer.”

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.