Mayflies 101: An Introduction to Different Types and Characteristics

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Mayflies are fascinating insects that draw quite the attention from nature lovers and scientists alike. With their slender bodies and delicate wings held upright, they are an attractive sight. Large compound eyes, short antennae, and two long, threadlike cerci on their rear add to their unique appearance.

In North America, there are currently 23 families and 108 genera of mayflies recognized. Each family and genus exhibits its own distinct features and characteristics, making them an interesting subject to explore further. As you embark on your journey into the world of mayflies, you will discover the astounding diversity that exists within this insect order.

Some common types of mayflies you might encounter include those from the Baetiscidae, Ephemeridae, and Caenidae families. While learning about their distinct features and feeding habits, you will get a better understanding of why these insects play important roles in their ecosystems and why their study is essential. So, let’s dive in and learn about the various types of mayflies you may come across in your explorations.

Overview of Mayflies

Mayflies, also known as Ephemeroptera, belong to the order Ephemeroptera, a group of insects found around liquid freshwater resources. These insects are diverse and provide various contributions to ecosystems, such as being a food source for other species. One interesting aspect of adult mayflies is their short lifespan, which can range from a few hours to a few days.

In the world of insects, mayflies hold a special place due to their unique qualities. For example, their aquatic nymphal stage, which is crucial to their development. Additionally, mayflies exhibit a wide range of feeding behaviors, which can vary across different families within the order.

Here is a brief look at some characteristics of mayflies:

  • Mayflies have delicate, transparent wings
  • Adults do not have functional mouthparts and don’t eat
  • Mayflies are an essential food source for fish and other predatory species
  • They are sensitive to water pollution and serve as bioindicators for water quality

When comparing mayflies with other insects, you’ll see that there are some key differences. For instance, mayflies have a unique life cycle involving multiple stages of development. This includes an egg stage, followed by a nymph stage, and then a subimago (pre-adult) stage before reaching full adulthood.

Considering the diversity of mayflies, it is important to recognize the role they play in ecosystems. Not only do they contribute to food chains, but they also serve as indicators for healthy aquatic environments. So, when you come across these fascinating insects, remember the remarkable characteristics that set them apart in the world of entomology.

Life Cycle of Mayflies

Nymph Stage

In the life cycle of mayflies, the nymph stage is the first and longest part. During this stage, mayfly larvae hatch from eggs and live in water. These aquatic nymphs undergo various molts, experiencing growth and development. As nymphs, they are sensitive to pollution and can often be found in high quality, minimally polluted sites like streams and rivers. Here are some key features of mayfly nymphs:

  • Aquatic habitat
  • Sensitivity to pollution
  • Molting for growth

Subimago Stage

After the nymph stage, mayflies enter the subimago stage, a unique phase in their life cycle. At this point, they transform into winged creatures, but they are not yet mature adults. The subimago stage is distinct among insects because mayflies are the only group to have it, making them truly remarkable. During this stage, one prominent change is the absence of functional mouthparts, as mentioned in this source.

Adult Stage

Finally, mayflies reach the adult stage, also known as the spinner or dayfly stage. In this stage, they have fully developed wings and mate in swarms. Adult mayflies are characterized by their large compound eyes, short antennae, and two long threadlike cerci at the end of their bodies, as described here.

Since adult mayflies have a very short lifespan, their primary purpose is reproduction. They mate shortly after reaching adulthood, and then females lay their eggs – often between 50 to 200 at a time – directly on the water’s surface, as seen in some species like Anopheles mosquitoes.

In summary:

  • Unique subimago stage
  • No functional mouthparts in subimago and adult stages
  • Adult mayflies mate in swarms
  • Females lay eggs in water

By understanding the life cycle of mayflies and their key characteristics, you can better appreciate the fascinating world of these aquatic insects.

Physical Characteristics

Size and Color

Mayflies come in various sizes and colors. Depending on the species, they can be found in shades of yellow, brown, and gray. The size of these insects can vary greatly, but they generally have a small-to-medium build.

  • Some mayflies are just a few millimeters in length.
  • Others can be up to several centimeters long.

Body Parts

A mayfly’s body is divided into three main parts: the head, thorax, and abdomen. Each of these parts has unique features that allow the mayfly to survive and thrive in its environment.


  • Contains large compound eyes for seeing their surroundings.
  • Short antennae are used for detecting signals from their environment.


  • Consists of three segments, each with a pair of legs.
  • The first pair of legs are typically held outward when perching.
  • The forewings and hindwings are attached to the thorax, which are essential for flight.


  • The slender portion of their body, housing vital organs.
  • Ends in two long, threadlike cerci that serve as sensory organs.

The mayfly’s forewings are much longer than the hindwings and often overlap them. Both sets of wings are known for their extensive veining, making them visibly distinct (source).

It’s important to appreciate the variety among mayflies in both size and color, as well as their distinct body parts, to better understand their place in the natural world.

Habitat and Distribution


Mayflies are mainly found in aquatic environments such as freshwater streams, ponds, and lakes. These delicate insects prefer clean water, making them sensitive indicators of water quality. As nymphs, they inhabit areas with rocks or submerged vegetation, providing protection from predators and a variety of food options. Some examples of typical mayfly habitats include:

  • Rocky or gravel-bottomed
  • Shallow ponds with submerged vegetation
  • Lakeshores with clean water


The distribution of mayflies is vast, spanning across North America and other parts of the world. They are particularly common in the United States, where a diverse range of species can be found. However, it’s worth noting that mayflies are not found in Antarctica, making it the only continent where these insects are absent. Here’s a summary of their global distribution:

  • North America: Mayflies are abundant in the continent, with 672 species in the United States alone.
  • Worldwide: Mayflies inhabit multiple continents, making them adaptable to various environmental conditions.
  • Antarctica: This is the only exception where mayflies are not present due to its extreme climate.

Overall, mayflies are known to thrive in aquatic habitats, primarily in freshwater ecosystems like streams, lakes, and ponds. their presence is notable in North America and several other regions across the globe, making them one of the most widespread insect groups in the world.

Mayflies As Part of the Food Chain

Diet of Mayflies

Mayflies, being an essential part of aquatic ecosystems, consume various food sources. As a nymph, you’ll find that they primarily feed on algae, diatoms, and detritus found at the bottom of rivers and streams.

  • Algae: provides a rich source of nutrients.
  • Diatoms: tiny, single-celled organisms that contain silica and are abundant in freshwater environments.
  • Detritus: decaying organic matter, including dead plants and animals.

By feeding on these sources, mayflies contribute to nutrient cycling and help maintain water quality.

Mayflies As Prey

In addition to being consumers, mayflies serve as a crucial food source for various animals. Both nymphs and adults are rich in protein, making them an attractive prey to many predators:

  • Fish: Due to their abundance in aquatic environments, mayflies represent a primary food source for many fish species.
  • Birds: Swarming adult mayflies attract a variety of bird species, which take advantage of this plentiful food source.
  • Bats: Bats are also known to eat adult mayflies, utilizing their echolocation abilities to find them in the air.
  • Spiders: Mayflies that rest on terrestrial surfaces can fall prey to spiders that take advantage of the opportunity to capture them.

As you can see, mayflies play an essential role in the food chain, providing sustenance to various predators while also contributing to maintaining the overall health of their aquatic ecosystems.

Role in Ecosystem

Mayflies play a crucial role in both aquatic and terrestrial ecosystems. They contribute significantly to the nutrient and carbon cycling between these habitats1. In their nymph stage, these aquatic insects consume various materials such as algae, living plants, dead leaves, wood, and even each other2.

Not only are mayflies important for the food chain, but their presence also serves as an indicator of water quality. In fact, the more mayflies you find in a water body, the cleaner it is3. Ecologists often rely on their populations for assessing the health of lakes, rivers, and streams4.

To give you an idea of their importance in the ecosystem, here are some key features of mayflies:

  • Vital for nutrient and carbon cycling between aquatic and terrestrial habitats1
  • Significant role in the food chain, especially in their nymph stage2
  • Serve as indicators of water quality and ecological health34

So, when you come across mayflies, remember their essential role in maintaining a healthy and balanced ecosystem.

Mayflies and Fly Fishing

Mayflies are a popular choice for fly fishing enthusiasts. These delicate insects are commonly found near streams and rivers, providing an abundant food source for trout and other fish. As an angler, knowing how to use mayflies as bait can significantly improve your fly fishing success.

Using mayflies as fishing flies can be highly effective in attracting trout. There are numerous mayfly species, each offering unique features that appeal to different fish.

  • Adams: A versatile fly pattern that resembles various mayfly species.
  • Blue Wing Olive: Ideal for overcast days, imitates smaller mayflies.
  • Pale Morning Dun: A popular choice during summer mornings and evenings.
  • March Brown: Effective in early spring when larger mayflies hatch.

It’s essential to match your fishing flies with the natural mayflies in your fishing location. Observe the mayflies’ size, color, and shape on the water, and select your artificial ones accordingly.

Pros and Cons of Using Mayflies as Bait

Pros Cons
Wide range of species Seasonal and regional limitations
Easily found in nature Vulnerable to damage
Attracts trout effectively Critically tied to specific hatches

Keep in mind that some mayfly species are more abundant during specific regional hatches. Always research the local mayfly population before planning your fly fishing trip.

Common Types of Mayflies

North American Species

There are numerous species of mayflies found in North America. For instance, the Purdue University’s Mayfly Central maintains a comprehensive database of North American species for study and identification. A few examples include the Drake, Ephoron leukon, and numerous species from the Baetidae family.

  • Drake: A large mayfly species, known for their robust size and important role as a food source for various fish species.
  • Ephoron leukon: Commonly called the “White Fly,” it is known for their synchronized swarms and significant local hatch events.

In addition to these species, the following families are also prevalent in North America:

  • Baetidae: Containing several species such as Baetis, these are fast swimmers and fusiform in shape.
  • Ametropodidae: Including species like Siphloplecton, this family exhibits a range of unique features among North American mayflies.

Worldwide Genera

Mayflies can be found across a wide range of habitats and countries. The diversity in mayfly genera contributes to the remarkable differences in size, habitat, and life cycles. Here are a few examples of genera found worldwide:

  • Heptageniidae: Includes the common flat mayfly, Stenonema, known for its flattened body shape.
  • Leptophlebiidae: Featuring species like Paraleptophlebia, these mayflies typically inhabit small streams and can be found worldwide.

The length and morphology of mayflies from different families can vary significantly. To better understand these differences, you can refer to the table below:

Family Example Species Length Range
Baetidae Baetis 0.2 – 0.4 inches
Heptageniidae Stenonema 0.4 – 1.0 inches
Leptophlebiidae Paraleptophlebia 0.3 – 0.6 inches

By understanding the species, classification, and characteristics of mayflies, you can better appreciate these fascinating aquatic insects and their importance within their ecosystems.

Other Names for Mayflies

You might be familiar with mayflies, but did you know that they have several other common names? These tiny, delicate insects are also known as shadflies, sandflies, and fishflies. Depending on the region, they might be referred to by different names, but the characteristics of these insects remain the same.

In the world of fishing, mayflies are often called ephemerons due to their brief adult lifespan. This name is derived from the word “ephemeral,” which means short-lived or temporary. Indeed, adult mayflies are known to live for only a few hours to a couple of days.

You can find mayflies belonging to various families across North America. With 23 recognized families and 108 genera of mayflies on this continent, it’s no wonder these insects have acquired so many common names.

Here’s a comparison table for your reference:

Common Name Fishing Name Scientific Name
Mayflies Ephemerons Ephemeroptera

So, the next time you encounter these fascinating insects in your surroundings, remember there are various names they go by, but their astonishing brief life cycle and role in the ecosystem remain consistent.

Conservation of Mayflies

Conserving mayflies is crucial due to their important contributions to ecosystems. As a keystone species, their presence is a good indicator of water quality. Here are some measures you can take to help protect mayflies and preserve their numbers:

  • Maintain water quality: Keep nearby water sources clean by properly disposing of waste, avoiding excessive use of chemicals, and minimizing sediment erosion.
  • Prevent habitat loss: Preserve and maintain natural habitats, such as wooded areas and riparian forests, where mayflies live and reproduce.
  • Educate others: Spread awareness about the importance of mayflies in ecosystems and their contributions to nutrient cycling, as well as their role as prey for various aquatic and terrestrial animals.

By supporting mayfly conservation, you can help maintain healthy ecosystems and contribute to their continued presence in the environment. Remember, every small action you take can make a difference in preserving these fascinating insects!


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Reader Emails

Over the years, our website, 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 – Summer Fishfly


Large Transparent winged Moth
Location: Bedford, Nova scotia, Canada
July 23, 2011 1:31 pm
Saw this one last night when the light in my porch attracted it. Thought it was a huge mosquito first, but see the moth like antanae in the photo. Body length about 4-5cm, quite large. Wings transparent. Never seen one like this before.
Signature: Wildlife Sightings,

Summer Fishfly

Dear Wildlife Sightings,
You have sighted a Summer Fishfly,
Chauliodes pectinicornis.  You can find information on the species on bugguide.  The pectinate antennae do resemble those of a moth.

Letter 2 – White Mayfly


Subject:  Unknown flying insect
Geographic location of the bug:  Anthem, AZ
Date: 03/13/2018
Time: 11:25 PM EDT
Your letter to the bugman:  I found a number of these while fishing a small urban pond. They seem to have a single pair of wings and three ‘tails’ for lack of a better term. I was fishing all day and these seemed to appear in greater number in the late afternoon to evening hours and seemed harmless enough.
How you want your letter signed:  Brian

White Mayfly

Dear Brian,
Though we recognized your insect as a Mayfly in the order Ephemeroptera, its appearance is quite different from other Mayflies in our archives.  We identified your individual as a White Mayfly, possibly
Ephoron album which is pictured on BugGuide, and though BugGuide does not report any sightings in Arizona, there are sightings from nearby Colorado and Utah.

Letter 3 – Spring Fishfly


need id on winged bug, please…
Location: seaford, va
May 4, 2011 7:16 pm
hi! i saw this bug hangin’ out on my steps and thought it was quite unique and interesting. it measured about 2 inches long. can you please identify it for me? thanks.
Signature: tina

Spring Fishfly

Hi Tina,
Though your Spring Fishfly,
Chauliodes rastricornis, is a large insect, she is dwarfed by her distant cousin the Dobsonfly.  The males of the species have feathered, comb-like or the more scientific pectinate antennae, while the antennae of the females are more linear with sawtooth edges.  According to BugGuide:  “Adults typically fly late spring: March?-May (North Carolina), April-May (West Virginia). Seen into early June in New England (Massachusetts–guide photo). Further south, much of year (Florida).”

Letter 4 – Summer Fishfly


Wed, Jun 17, 2009 at 7:14 PM
Hi Lisa and Daniel,
I can’t figure out if this is a lacewing or a moth or neither (the antennae are throwing me off). I researched numerous images online but can’t find a picture of it. Any ideas?
Katherine Gividen
Tylertown, Mississippi

Summer Fishfly
Summer Fishfly

Hi Katherine,
This is a Summer Fishfly, Chauliodes pectinicornis, which differs from the related Dobsonfly in that the Summer Fishfly has combed or pectinate antennae while those of Dobsonflies are threadlike or beadlike.  Both insects are in the order Megaloptera and the Family Corydalidae.   According to BugGuide:  “Larvae aquatic, omnivorous: detritivores, or herbivores, also predatory on other invertebrates.  Larvae tend to live in calm bodies of water with lots of detritus. Larvae leave the water to pupate under bark, inside rotting logs. Pupation takes approximately 10 days. Adults emerge to mate, live perhaps a week. There appears to be just one flight per year, and the life cycle may be just one year, though older references quote a 2-3 year life cycle. Eggs are laid in masses on vegetation near still bodies of water. Larvae hatch and crawl to water. ”  We will be posting your letter and photo between tow letters and photos of Dobsonflies for comparison.

Letter 5 – Spring Fishfly


Subject: Is this some type of dobsonfly?
Location: Blackshear, GA, USA
March 18, 2015 8:46 pm
I found this guy near my front porch. Seemed drawn to the porch light, but not too great a flier. Can’t find anything looking like it to know exactly what it is.
Signature: Hil

Spring Fishfly
Spring Fishfly

Dear Hil,
This Spring Fishfly,
Chauliodes rastricornis, is closely related to the Dobsonfly, but it is a much smaller insect.  Your individual is a female as evidenced by her serrated antennae.  According to BugGuide:  “The antennae of females are serrate (saw-like):  The comb-like, (pectinate) antennae of the males are quite obvious.”  Sightings in Georgia occur in March and April according to BugGuide.

Spring Fishfly
Spring Fishfly

Letter 6 – Spring Fishfly


Subject: Mystery moth
Location: Powell, Ohio
May 7, 2015 2:04 pm
Saw this moth at the kids’ school today. Never seen one before. Assuming it’s male, cause of the fuzzy antennae. Columbus, Ohio area, lots of woods, ponds and streams around.
Signature: Amber

Spring Fishfly
Spring Fishfly

Dear Amber,
Though it has some mothlike qualities, this Spring Fishfly,
Chauliodes rastricornis, is not even closely related to a moth, though your speculation that it is a male insect because of the antennae is correct.  According to BugGuide, they are found:  “Near calm bodies of water with detritus.” 

Letter 7 – Spring Fishfly


Subject: Dobsonfly
Location: 34.7791, -82.3564
April 19, 2017 7:45 pm
Hi Bugman,
I encountered this customer while monitoring frog calls at Lake Conestee nature park. It was around 2120 local time on April 19, 2017, roughly forty to fifty minutes after sunset. I was sitting on a wooden boardwalk/bridge over an area of weedy water. The wind was calm, and the temperature was around 18 degrees Celcius, or 291 K. The insect was irrisistably attracted to the luminescent emission of my advanced wireless communication device. I suspect that it is a Dobsonfly, specifically Corydalus cornutus. I would like a second opinion, however.
Thank you for your time,
Signature: A Biology Student

Spring Fishfly

Dear Biology Student,
You are mistaken, though this Spring Fishfly,
Chauliodes rastricornis, is in the same family as the Eastern Dobsonfly.  Spring Fishflies are much smaller than Dobsonflies and they have different antennae.  According to BugGuide:  “The antennae of females are serrate (saw-like) The comb-like, (pectinate) antennae of the males are quite obvious” meaning your Spring Fishfly is a male.

Intersting. Yes, that makes sense. Thank you so much. The antennae intrigued me, because the antennae did look male. I had never seen insects from that family before. There is a reason why I am still a student…
Have a great day.
A Biology Student who must study more

Letter 8 – Spring Fishfly


Subject: Is this a moth or bee
Location: New Jersey
May 2, 2017 2:09 am
This insect was on my screen door. He never left the whole day. We actually thought it was dead but it left later in the day. On the underside his body was long and thin. Can you identify?
Signature: Me Ma

Spring Fishfly

Dear Me Ma,
This is neither a moth nor a bee.  It is a female Spring Fishfly.

Thanks for your response. It’s the first one we’ve seen in our area.  It’s actually still on our screen door.


Letter 9 – Spring Fishfly


Subject: CReaPY
Location: Northern Indiana
May 27, 2017 4:25 pm
Just wondering if its a good bug or bad bug
Signature: IDK

Spring Fishfly

Dear IDK,
Good and Bad are such relative terms when it comes to insects.  This is a male Spring Fishfly,
Chauliodes rastricornis, and it is not a threat in any way to humans.  According to BugGuide:  “Adults typically fly late spring: March?-May (North Carolina), April-May (West Virginia). Seen into June and even early July in New England (see Massachusetts records). Further south (Florida), this species is seen much of year.”  The genus is mentioned on TroutNut, which means anglers will use adult and larval Fishflies for bait.

Letter 10 – Spring Fishfly


Subject: This thing looks like it flew out of Satan’s Butt
Location: Farmington MN USA
June 9, 2017 2:24 pm
Thank you for taking the time to identify this insect for me! We saw it this one time as depicted in the photo in Farmington MN(Southern suburb)on June 12th of last year, and haven’t seen it since.
As you can tell by my description, I find it hella ugly, and hope I never see it again.
Signature: Matthew

Spring Fishfly

Dear Matthew,
If you were creeped out by this harmless male Spring Fishfly, we wonder how tou will react upon encountering its larger and also harmless relative, the male Eastern Dobsonfly.

Letter 11 – Spring Fishfly


Subject: interesting bug
Location: northern Illinois/Chicago suburbs
July 27, 2013 1:42 pm
I live in northern Illinois and found this guy outside this morning. It is maybe about an inch long, greenish grey, and long wings. Any ideas?
Signature: Stacy

Spring Fishfly

Hi Stacy,
You must live near a source of water.  This is a Stonefly in the order Plecoptera, but we are uncertain of the species.  See BugGuide for more information on Stoneflies.

Thanks so much!  Yes, there is a marshy area across the street.  The weather up where we are has been unusually cold, so I think he was sunning himself on our house for a good part of the day.  I looked up the info on a Stonefly and for sure, it’s a match!  Thanks for the info and the quick response.  I appreciate it.

Correction:   Spring Fishfly
August 17, 2013
Thanks to a comment from Joshua, we are admitting that in a hurry we misidentified this Fishfly, mistaking it for a Stonefly.  See BugGuide for a matching image of a female Spring Fishfly,
Chauliodes rastricornis.

Letter 12 – Summer Fishfly


cicada, moth, dragonfly cross?
Hi my name is jesse dovick and I live in Welland, Ontario, Canada. I was in my friends shed when this thing flew in. I thought it was a moth but then noticed it had dragonfly like wings with no powder. also it has 2 wicked fangs and 6 other mandible type things. I coaxed it to ride on my finger to my house so i could photograph it. It has cicada like patterns on it. I’m quite curious to find out what this bug is. see enclosed pics
jesse dovick

Hi Jesse,
This is a Summer Fishfly, Chauliodes pectinicornis. It can be distinguished from its larger and more impressive cousin, the Dobsonfly, by the combed antennae.

Letter 13 – Summer Fishfly


Location:  Glen Arbor, MI
August 4, 2010 7:56 pm
Found this bug in Glen Arbor, MI on August 3. I’ve never seen anything like it up there before. Can you help? Thanks!!
Erin Brotherton

Summer Fishfly

Hi Erin,
This is a Summer Fishfly,
Chauliodes pectinicornis, and you may compare your image to the ones posted to BugGuide.

Letter 14 – Summer Fishfly


evening visitor
Location: Putnam County, NY
August 9, 2011 7:55 am
This fellow was flying around in our house on two successive evenings. Caught him last night to examine him. Has wings like a dragonfly and a body unlike a dragonfly.
I live in lower NY state, Putnam County.
Signature: Jude

Summer Fishfly

Hey Jude,
This is a Summer Fish Fly,
Chauliodes pectinicornis, and it can be distinguished from the similar looking but even larger Eastern Dobsonfly by the pectinate or combed antennae.

Letter 15 – Summer Fishfly


Subject: It was so large I thought it was a baby bat when it flew by me.
Location: Massachusetts
July 12, 2013 10:00 pm
It flew into my house at night, and I live in Massachusetts. It was about 60 degrees out, and I don’t live too far from a swamp and there is a horse barn close to my house too. It’s really about 4-5ish inches long, the fork behind it is just at an odd angle. Like the subject says, when it flew past me I thought it was a baby bat.
Signature: Mary

Summer Fishfly
Summer Fishfly

Hi Mary,
Catchy subject lines always grab our attention.  This is a Summer Fishfly,
Chauliodes pectinicornis, and your location near a swamp is significant.  The pectinate antennae distinguish Fishflies from Dobsonflies.  According to BugGuide, Summer Fishflies are found:  “Near ponds, lakes, quiet parts of streams. (Contrast this with Dobsonflies, which inhabit streams as larvae.) Adults come to lights.” 

Letter 16 – Summer Fishfly


Subject: Strange bug
Location: Northern Indiana
July 15, 2013 10:17 pm
This evening as my husband and I were turning off the lights in our house he spotted a large bug on our sliding glass door and thought it was a dragon fly so I walked over to take a look. I thought it had to be some weird kind of moth from the colors. After searching the web I couldn’t find anything that looked similar to it, and any help identifying it would be great!
Signature: Thank you, Erin

Summer Fishfly
Summer Fishfly

Dear Erin,
The pectinate antennae distinguishes this Summer Fishfly from the related, and even larger female Dobsonfly,
which has monofiliform or beaded antennae.

Letter 17 – Summer Fishfly


Subject: What IS this thing?!
Location: Catskills, NY
July 16, 2014 3:26 pm
This bizarre looking bug was just outside the door last night. It seemed to be having trouble landing on the siding of the house, but was exceptionally persistant to find purchase on the faux wood. As it came into the light, it struck me just how strange it appeared. As far as I could tell, it had a head and mandables that somewhat resemble a large ant or perhaps even a terminte, though it’s legs had tiny ridges that made them more resemble the legs of a house fly. As the below pictures show, it’s eyes protrude slightly from it’s head, just below a set of large feather-like antenna that I would expect to see on a moth. It’s body was very long like that of a dragonfly, yet at the same time surprisingly plump much like a gypsy moth. Though the piture does not show it, it had a set of four wings, all of them crystal clear, with vainy dark lines through them as would be found on a dragonfly or cicada. I suspect it may be nocturnal, as it was very clumsy la st evening in it’s movements and flight. At some point, it managed to find a way into the house, and went straight for the wooden cabnets before dissipearing into some dark and unknown location. It seems to like wood quite a lot. Early this morning it was found again in the kitchen, virtually unmoving as it perched in the the darkened sink corner behind a mug. However, it seemed fine once released again outside. I’m far from an expert on the matter, and have been searching google off and on for a large portion of the day. I have never in my life seen anything quite like this bug, and I can’t help feeling a certian mixture of confusion and awe as to what it might be. Any help at all in possibly identifying it would be greatly appreciated. Thank you in advance for any help you might provide.
Signature: Simply Baffled


Dear Simply Baffled,
Your Summer Fishfly,
Chauliodes pectinicornis, is in the family Corydalidae along with the considerably larger Dobsonflies.

Letter 18 – Summer Fishfly


Subject:  What’s this bug?
Geographic location of the bug:  Connecticut
Date: 08/13/2018
Time: 04:19 PM EDT
Your letter to the bugman:  Hey there!
I’m a horticulturist at a brewery in Connecticut. This insect is resting on one of my etrog trees in my citrus greenhouse. It’s about 2” long from wingtip to antennae. Thanks much!
How you want your letter signed:  Chloe

Male Summer Fishfly

Hi Chloe,
Because of your request, we learned that an etrog is a type of citrus.  Your insect is a male Summer Fishfly,
Chauliodes pectinicornis, and you can verify that by comparing your image to this BugGuide image.  According to BugGuide:  “prefer shaded, woodland habitats” which might have led it to your greenhouse.  Of the genus, BugGuide notes:  “larvae in slow-moving waters with lots of detritus, esp. decaying logs” so we suspect you have a sluggish stream nearby.  It poses no threat to your etrog or to any other plants in your greenhouse because BugGuide notes:  “adults may not feed” and “Adults live a week or less.”

Letter 19 – Summer Fishfly


Subject:  A flying bug
Geographic location of the bug:  Ct
Date: 08/14/2018
Time: 09:35 AM EDT
Your letter to the bugman:  I am just wondering if you know what this might be. I found it quite still in a bathroom closet, but when I picked it up it moved.
How you want your letter signed:  Bug watcher in CT

Summer Fishfly

Dear Bug watcher in CT,
This is a Summer Fishfly, and in the past 24 hours, we posted another image of a Summer Fishfly from Connecticut.

From what other people have said via facebook agricultural pages, mine was a female Dobson Fly. They say that they are similar…? Anyway, I have seen that the males have very large mandible, larger than this one.

Same family.  Different species.  Female Dobsonfly has very different antennae.  See BugGuide.

Cool, thanks! Insects have always been fascinating to me. It astonishes me how many different varieties there are that some people will never see in their lives.


Letter 20 – Summer Fishfly


Subject:  Interesting insect I have never seen here
Geographic location of the bug:  Waltham, MA
Date: 09/03/2021
Your letter to the bugman:  I found this resting on a lawn chair 8/20/21. He/she was 1.3 inches, not counting antennae. He stayed very still, didn’t move, even when I moved the chair across the yard. I took this photo. He stayed still all day, and next day, he was gone. I live at edge of very wet, dense wild woods & see many interesting insects. Never saw one like him! Can you please help? Thanks!
How you want your letter signed:  Kalani Cross

Summer Fishfly

Dear Kalani,
This is a Summer Fishfly.  According to BugGuide:  “prefer shaded, woodland habitats” which is what your “wet, dense wild woods” provides.

Oh, thank you so much!  Such a fast reply, and the most exciting news!  I really wanted to know what he is, and now I can read all about him!  YOU ARE AWSOME!  THANKS!

Letter 21 – Summer Fishfly: Disembodied Head


Spiral antennae, brown body, yellow fangs, half inch tall
July 31, 2009
I was outside playing with my kids and happened to glance over at my husband’s truck and saw this bug. I’ve never seen anything like it in my life and I’m very curious to know what it is. I’m not going to lie, I was very afraid to get too close so I am hoping that my picture is clear enough to see details. The bug is probably a half an inch tall, brown with some yellow, and appears to have a hard shell.
Syracuse, New York

Summer Fishfly: Disembodied Head
Summer Fishfly: Disembodied Head

Hi Stephanie,
This is the disembodied head of a Summer Fishfly, Chauliodes pectinicornis, which may be matched to an image on BugGuide.  The form of the pectinate antennae indicate that this was a male Summer Fishfly.  How it was disembodied is a curious question, and we suspect a predator like a bird or bat made a snack of the nutritious body.  Summer Fishflies have long bodies and an impressive wingspan.  What you saw only represents about 15% to 20% of the entire insect length.

Letter 22 – Summer Fishfly Impaled: Unnecessary Carnage


What’s this bug I found?
August 9, 2009
I found this bug in my tool box at work. It was a very week flyer. I placed the corner of a newspaper near its mouth and it bit into it. The jaws were like a big ant.
Scott A. E. (ed. note:  surname withheld to prevent positive identification and potential public ridicule)
Niagara Falls, NY

Summer Fishfly Impaled
Summer Fishfly Impaled

Dear Scott,
This is a Summer Fishfly, Chauliodes pectinicornis.  According to BugGuide, the species name pectinicornis means comb-horned and refers to the antennae which are quite different from the similar looking though considerably larger Dobsonfly.
We doubt that you are beginning an insect collection as the object that has impaled this Summer Fishfly does not appear to be an entomologist specimen pin.  This is speculation on our part, but we suspect this living Summer Fishfly was impaled to keep if from escaping so that it could be photographed, and it might have still been alive when the photo was taken.  In our minds (and perhaps also the minds of some of our readership) this would constitute Unnecessary Carnage.  We have taken the liberty of editing your surname from our posting in the event that friends and acquaintances of yours happen to read this posting since we are being careful about defamation of character. Other than to say that the jaws of the Summer Fishfly bit into a newspaper, you did not indicate that you were threatened by it, and since Summer Fishflies are perfectly harmless, we feel that there was no need to kill this insect.

Letter 23 – Summer Fishfly, we believe


Identification Request: not a Dobsonfly but what?
Location: Stillman Valley, IL
May 15, 2012 9:33 am
Hello Bugman,
Long time fan Amy B. here..I noticed this not so little guy on my screen this morning. At first I thought I was looking at a male Dobsonfly, but then I noticed the ”feathery” antennae so that made me second guess myself. What is it?I looked around a bit to try to find it, but the baby is keeping me from doing very much searching. There is one photo with the corner of our newspaper in it to give an idea of scale..I’d say it was about an inch and three quarters with the antennae. I live in northern Illinois near a creek. Let me know when you get a minute, would ya? Sincerest thanks!
Signature: Huge fan of the site

Summer Fishfly

Dear Amy,
Thank you for your kind compliments.  Your confusion is easily explained.  We believe this is a Summer Fishfly,
Chauliodes pectinicornis, and it is closely related to the Dobsonflies which are in the same family Corydalidae.  According to BugGuide:  “Both sexes have pectinate antennae. Flies, probably, more in mid to late summer than the more spring-flying C. rastricornis. Head and pronotum have yellow markings on dark brown background, compared to dark markings on yellowish background in C. rastricornis.”  The description is closer to the Summer Fishfly, though the sighting in May tends to indicate this might be the closely related and very similar looking Spring Fishfly, Chauliodes rastricornis, which is also profiled on BugGuide.

Thanks so much! I had come to the same conclusion during a nap the baby was taking that allowed me to search a little more. I’ve never seen anything related and always had hoped to see a Dobsonfly in person especially after seeing how big they get in some of the pics. This guy stayed on the screen all day until the sun set and then took off for his own adventures. It was a pleasure to have his company for the day and I was honored. Thanks again Bugman for all the work you do in keeping us in the know!!
Very sincerely,
Amy Berogan

Letter 24 – Swarming Mayflies


A Zillion Mayflies
May 24, 2010
Thought you might enjoy the photo.
This was taken on a family camping trip in 2003 if I remember correctly.
I walked to the bathroom without a flashlight the night they all came out. I thought the crunchy things I kept stepping on were just leaves, until I reached the bathroom, which had lights… That’s the last time I can recall ever running around barefoot in the dark.
Camp in Manistique, MI

Swarming Mayflies

Dear DD,
Thanks for the wonderful photo and field observations.

Letter 25 – Turkish Mayfly Metamorphosis


another photo for you…
Dear Bugman,
Not a dead fly, but an interesting ‘phenomenon’ we saw on the wall of our house… It seems that the fly has changed it’s skin (exoskeleton?) and is waiting for the new one to dry before flying off! No idea what it is but thought it may be good for your pages. I was wondering whether the wings are ‘renewed’ at the same time or not – but there seem to be shrivelled wings on the old ‘case’… Best wishes, keep up the good work…
Abdullah Eyles
Ceyhan, Turkey

Hi Abdullah,
Members of the order Ephemeroptera are known as Mayflies in the U.S. We don’t know if they have an equally descriptive name in Turkey. Larval Mayflies are aquatic, so you must have a water source, pond or fountain, in the very near vicinity. Mayflies have incomplete metamorphosis. The aquatic nymphs, or naiads, have no wings, and after the final molt, the winged adult emerges. Mayflies are short lived as adults and do not feed.

Letter 26 – Two Mayflies


fours and fives in PA
We are a class of 4 and 5 year olds in PA. You have helped us before identifying bugs and we hope you can help again. We search our playground daily for bugs, photograph them and then hang them on our wall [we included a photo]. We have then been using your site to help us identify what we find. We have figured out most of them now [hopefully correctly] but are stumped on a couple. THANK YOU VERY VERY MUCH BUGMAN!
Fours and Fives in PA

Hi again Fours and Fives,
Both of these photos are of Mayflies. The photos look so nice together. Your BugWall is pretty awesome.


  • Bugman

    Bugman aka Daniel Marlos has been identifying bugs since 1999. 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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Tags: Mayfly

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17 Comments. Leave new

  • Awesome, thanks for the id.

  • I wouldn’t say stonefly, check out Fishflies, genus Chauliodes in Megaloptera.

    • Thanks for the correction. That will teach us to be more careful when postdating over thirty letters in a short period of time. We got a bit careless.

  • No Longer Baffled
    July 17, 2014 10:21 am

    Thank you so much for your help. For something supposedly so well known, it was next to impossible to find anything that even resembled it online without knowing it’s name. Then again, that could be attribuited to what little time I had to really look into the issue. My home is currently undergoing renevations, so now I just have to hope this little guy came from one of the nearby stream beds, rather then inside one of the walls. I’ll be checking out the new external ‘basement’ later today. As cool as this bug was, I’m really hoping all the recent rains haven’t caused the basement to flood and turn into a potential spawning ground, especially since they seem to know ways to get into the house now…

  • Stone fly ?

  • It just flow through my window in my room and I said to myself WHÀT IS THAT

  • My husband saw this hugh bug with about a 3 inch wing span yesterday. Today, after a rain he found it on the sidewalk, dead. Since we have never seen one like it before in southern Missouri I checked the computer. This bug is 3 1/2 inches long from front tentacles to tail end, has cross over wings, light colored, (almost translucent) with dark markings. It looks like the bug pictured.

  • Just spotted one on my porch. Southeast Georgia.

  • they are right Katherine it’s a summer fish fly

  • Talking abot (summer fishfly) Yesterday feb 15 2018 night
    in My car garage one of this insect was atract to the light bolb , I took a picture and send it to my wife to find if this species is dangerous or harmless , why kill a insect if you dont know the origen or specie , Im glad to see one of this
    Visit my home , before you touch or kill any insects use your phone and search
    I open my garage door and she or he fly away
    Beautiful creature ( the picture with the nail I dont mind , but my wife got angry )

  • Just saw one of these in Conroe Texas

  • Just spotted one of these tonight, flying up against our window screen. SE Pennsylvania.

  • Kim Strickland
    July 18, 2023 11:58 am

    Found one on my friends porch in upstate Owego NY!


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