10 Dobsonfly Interesting Facts (And Their Larvae Too)

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Dobsonfly Interesting Facts

Discover the World of Dobsonflies: 10 Fascinating Facts

Did you know that DC comics launched a whole villain named after the larvae of dobsonflies? Read on to learn more such interesting facts about these insects.

The insect world never fails to amaze us with its diversity. If you are into nature and love to learn about insect species, the dobsonfly should pique your interest like no other moth.

The dobsonfly is one of the largest members of the insect world. It starts its life out as an aquatic bug and ends it flying in the skies.

It is most common in the Western Hemisphere, although you may also come across them in Central and North America.

Currently, there are30 species of dobsonflies around the world, but only one is common in the United States: the eastern dobsonfly (Corydalus cornutus)

Dobsonfly Interesting Facts

Dobsonfly Interesting Facts

So, of all insects in the world, why would you want to learn more about dobsonflies? Let’s have a quick look at some dobsonfly facts:

They live their entire lives as larvae.

The life cycle of a dobsonfly is one of the most intriguing details about this species. The bug gets to spend only a tiny fraction of its life cycle as a mature adult.

The larval stage alone lasts three to four years, making the total lifespan of a dobsonfly quite impressive.

After this, the pupal stage lasts a few months, from winter to spring. Once the adults emerge, they live only up to a week at most – just enough to reproduce.

Hence, despite having a total lifespan of several years, these moths live only a few days as adults.

The adult stage is so short that at this point, they don’t even eat! They use their food stores from the pupae stage to find a mate and bring the next generation forward.

Dobsonfly Interesting Facts

These bugs are hard to find: they only live near running water.

Dobsonflies are quite common, and you can find them all over the world. However, they’re especially abundant in Africa and Asian countries like Vietnam and China.

You can also find dobsonflies in Australia, Central America, and North America, although their subspecies aren’t as diverse in the western part of the world.

In the US, you will mostly find the eastern dobsonfly. In total, there are nine genera of dobsonflies, comprising dozens of species in total.

Their habitat is limited to places that are near rivers or running streams of water, where they live their lives as larvae, and then even as moths, they don’t go very far.

Some of them are large enough to cover your face.

Remember we mentioned that the dobsonfly is one of the world’s largest insects? You might be wondering exactly how big they are.

Well, these bugs can grow up to five inches long, and their wingspan may reach up to eight inches.

To give you a more visual example, a dobsonfly is large enough to cover most of your face. Don’t try to imagine it, or else you will have nightmares for the rest of the week!

However, not all species of dobsonflies are equally large. The five-inch-long ones are more predominant in Asian countries, especially China and Vietnam.

Some dobsonfly species are only two to three inches long. Moreover, the females are significantly shorter, not the least because they don’t have large mandibles in the front.

Regardless, this doesn’t rule out the fact that the dobsonfly has impressive dimensions.

Dobsonfly Interesting Facts

They look like something out of a horror movie.

Dobsonflies share quite a resemblance with dragonflies, especially with their wings spread apart. Like dragonflies, they have four veined and translucent wings.

However, dobsonflies cannot fly as well as dragonflies.

The color of these soft-bodied insects varies between yellow and dark brown. The exoskeleton comprises three segments, and like most insects, dobsonflies have three pairs of legs.

The mandibles of a dobsonfly are easily noticeable due to their large size and sickle-like shape.

Although the adult forms vary from one subspecies to another, the basic shape and structure mostly remain the same.

Despite their appearance, they are mostly harmless.

The large size of a male dobsonfly, together with their sickle-shaped mandibles, can make them quite scary, but those mandibles are all bark and no bite. The real biters are the females.

The males cannot bite – the mandibles are mostly used to defend against mating rivals. Even if a male dobsonfly bites you, it would just feel like a strong poke because the mandibles don’t have enough leverage to do any serious harm.

However, we can’t say the same about female dobsonflies.

Although the female dobsonflies have smaller jaws, their mandibles are strong, and they have sharp pincers capable of dealing powerful bites.

If you handle one of them carelessly, you might even end up with a bleeding wound. However, you can breathe a sigh of relief since they won’t bite you deliberately agitate them.

Thankfully, neither the males nor the females are venomous, and the pain from the bite doesn’t last very long.

The larvae form of dobsonflies is called hellgrammite – and these critters are also strong biters. However, you would be hard-pressed to find one around since they live in the water.

Dobsonfly Interesting Facts

They don’t like flying, but they aren’t bad at it either.

Despite having large wings similar to dragonflies, these bugs are nowhere as good as dragonflies when it comes to flying.

Although their exact flight speed is still unknown, they fly in a rather shaky and trembling manner.

However, they can still cover a significant distance when looking for a new water body.

Hellgrammite Interesting Facts

Now that you gathered some interesting knowledge about dobsonflies let’s learn about the larvae of dobsonflies – the hellgrammites.

The insect spends most of its time in the larval stage: this article would be incomplete if it didn’t cover hellgrammites as well.

Dobsonfly Interesting Facts

They live their lives underwater.

Unlike adult dobsonflies, which move to land after pupation, hellgrammites are completely aquatic.

They prefer to live in shallow and fast-flowing parts of rivers, streams, and creaks, usually hiding under logs or rocks.

One of the most interesting things about hellgrammites is that they prefer to live in clean waters with well-balanced pH levels.

If you find these larval bugs in your backyard pond or dobsonflies near it, that means your pond is quite clean.

Even trace amounts of pollutants cause these insects to seek a different water body.

They eat a lot of aquatic pests and are great for keeping water bodies clean.

While dobsonflies don’t feed as adults, their larvae are aggressive predators in the water.

Hellgrammites hunt and feed on a variety of other aquatic insects, mayflies, immature chironomid midges, stoneflies, and even small fish.

Also, you should note that hellgrammites are fish food themselves. Anglers often use these larval insects as fish bait.

Dobsonfly Interesting Facts

DC named a comic villain after them.

This insect looks a tad gross in their larval stage, somewhat resembling a centipede. They are so ugly; DC actually made a comic villain named after them!

They are generally black, tan, or dark brown, with flattened and elongated bodies.

In addition to the three pairs of legs, the abdomen also has eight pairs of leg-like appendages on the sides. Each of these appendages has a hairy or cottony gill tuft at the tip.

Each of the actual legs has a tiny pair of pincers beside the mandibles in front of the thorax.

Hellgrammites also have a pair of hooked leg-like appendages at their rear end that allows them to anchor to the surface and prevent themselves from getting washed away in the current.

They are usually two to four inches long.

They live their lives in the water, but that’s not where they lay eggs

Although hellgrammites are aquatic, adult dobsonflies don’t lay eggs in water.

Instead, they lay eggs in shady vegetated areas adjacent to water bodies or rocks poking out of the water’s surface.

Female dobsonflies can lay up to 3,000 eggs in the form of large egg masses. These egg masses resemble bird droppings which often get overlooked by predators.

The eggs take about two weeks to hatch. Once it’s time, the egg mass turns liquid. The hatchlings can now drop into the water and continue their lifecycle.

Dobsonfly Interesting Facts

Wrap Up

We hope by now we have been able to pique your interest in dobsonflies! These insects look really scary, but they are actually gentle creatures who can’t do you much harm.

Thank you for reading, and keep on exploring the amazing world of insects!

Reader Emails

Considering their size and wingspan, it is no wonder that many of our readers have had an avid interest in these bugs.

Read a bit more about the interesting conversations that we have had with our readers regarding Dobsonflies over the years in the emails below.

Letter 1 – Dobsonfly

 


Any idea what this is?? Never seen this before in Townsend Massachusetts. Thx,
Erik

Hi Erik,
This is a male Dobsonfly.

Letter 2 – Dobsonfly

 

5 inches long with wings, and maybe pinchers??
We found this on the top of our garage. It’s about 5 inches long, kind of reminds me of a cicada(sp?) but is bigger than those I’ve seen … and looks like it has pinchers of some kind. I didn’t see one on your site and was wondering if you know what it is? I know you’re very busy but if it fits in your schedule, we’d love some help identifying it. Thank you,,
Hilary Evans

Hi Hilary,
We are very surprised that we haven’t gotten more requests this year for Dobsonflies. June and July are generally our peak months for sightings. Male Dobsonflies have those signature mandibles that make it virtually impossible to confuse this species to any other.

Letter 3 – Dobsonflies and Fishflies

 

Thanks for having this “little” guy on you page. I’ve seen Hellgramites before, but I never knew what they grew into. I spotted this one on the ash tray outside our office this morning. I thought you might like to add the picture to your collection.
Thanks!
Bob

Thanks for the great photo Bob.

Letter 4 – Dobsonflies and Fishflies

 

Hi!
I live in Austin, Texas and just found this nasty looking bug outside on my patio, clinging to the wall in the early morning below my porch light.
It has a large set of mean-looking pincers on the front of the head. The forward half of the body is dark, and the rear half is light tan and caterpillar-looking. I had to take the picture through the yogurt jar I captured him in. He is about 3.5 inches long.
I leave most outdoor bugs alone but was concerned that if I ran across him later accidentally, I might get a nasty bite. He aggressively threatened me as I repositioned the jar to get the photo.
If anybody wants him, come and get him!
Thanks!
Patty Pritchett


Dear Patty,
She is beautiful. He is an adult Dobson Fly, the larvae of which are known as Hellgrammites. The male has even moreformidable jaws which are used during the mating ritual in what humans might consider spousal abuse. They will not harm humans. We have additional information on our site.

 

Letter 5 – Dobsonflies welcome in Summer

 

Ed. NOte:  Summer Sightings
With summer here, we expect to be getting numerous identification requests for Dobsonflies.  We thought this posting showing a beautiful male and female Dobsonfly from two different areas will help our readership identify this distinctive creature.

Identify bug
Location: Asheville NC
June 21, 2011 8:11 am
We saw this in Asheville NC on June 20. It was 3 – 4 inches long and on a fence post.
Signature: SCBrit

Male Dobsonfly

Please Identify our bug
Location: N. Ky.
June 21, 2011 10:32 am
This insect was found up inside of our umbrella. The body portion of the bug is almost as long as my pinky finger. This pic was taken in N. Kentucky, today, June 21, 2011. I have lived in Ky. my whole life and I cannot say that I have ever seen this before.
Signature: Marlene Shoemaker and kids

Female Dobsonfly

Dobsonflies are fascinating insects that display pronounced sexual dimorphism.  The larger male also has significantly larger and differently shaped mandibles.  Larval Dobsonflies are known as Hellgrammites.

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 – Hellgrammite from California

 

Majave River
Location: Mojave River, Southern Califorina
July 4, 2011 3:40 pm
We were at the Mojave River and saw this bug in the water. It kinda looks like a larva of some sort, but in all honesty i have no idea what it is and was hoping you would be able to identify it for us.
Thanks for your time
Signature: The Green Family

Hellgrammite

Dear Green Family,
This is the larva of a Dobsonfly, commonly called a Hellgrammite.  Most of our specimens are of the Eastern Dobsonfly, though several species are known to range in California, however they are not well documented.  This is one of the Western Dobsonflies.  See BugGuide for additional information.

Letter 2 – Hellgrammite in the Snow!!!

 

snow insect
Location: mt rainier national park, washington state
February 25, 2012 2:20 am
we saw this 6 legged, spiny insect on a snowshoe in mt. rainier national park (washington) late feb 2012. from limited, ignorant research– it looks similar to firefly and lacewing larvae but not exact. wished we would have put something down there to show size-but didn’t- was at least 2 inches long. thanks
Signature: jen

Hellgrammite in the Snow

Dear Jen,
This sure looks to us like a Hellgrammite, the larva of the Dobsonfly.  Interestingly, BugGuide has a photo, also from Washington, that was posted two years ago in February.  That individual is also in the snow and there was speculation about why it was in the snow.

Thank you so much-  very nice to get an answer so quickly.  we were right next to a spring fed beaver pond with numerous geothermal springs/vents.  if that makes any difference with the strange location (snow) of a typical aquatic  bug.
Again- thanks again-
Jen

Hi Jen,
Those details might be significant, but it is still interesting that there was another Hellgrammite sighting in Washington in the snow.

Letter 3 – Hellgrammite

 

crazy ant like centipede
Location: tennessee mountains
April 9, 2012 10:13 am
this was found under a rock near a river bank, it tried to burrow into the dirt. It is spring and this was found near a cool mountain river. thanks for your time. it is about 4 nches long and maybe a half inch across the little things on its side do not move like legs..?  this bug is about 4 inches long and a half inch wide. It was found under a rock on a pebble river bank in the tennessee mountains. it’s back ”legs” dont move and it was trying to burrow under a small plant.
Signature: Heather Brannon

Hellgrammite

Hi Heather,
You are not the first person who has mistaken a Hellgrammite for a Centipede.  Hellgrammites are the larval form of Dobsonflies.  Though they are not venomous and are not considered dangerous, both immature Hellgrammites and fully grown female Dobsonflies are capable of inflicting a painful bite if carelessly handled.  Male Dobsonflies, despite their formidable looking mandibles, are not capable of biting humans.  Hellgrammites are a prized bait among freshwater anglers.

Letter 4 – Hellgrammite

 

Subject: what is this bug?
Location: Coventry,Ct
May 23, 2012 6:47 am
Mr.Bugman,what is this bug?My husband found it on a job site.It even attacked the tape messure when holding it up to it with his pinchers.
Signature: thanks sheri

Hellgrammite

Hi Sheri,
Try as we might, we have never been able to trace the origin or meaning of the name Hellgrammite, however it seems a very appropriate name for this Dobsonfly Larva.  If you think the larva is a fierce looking creature, take a peek at this adult male.  Dobsonflies and Hellgrammites are harmless, though it is possible to get a nip if the larva or adult female is carelessly handled.  The mandibles of the male are showstoppers, however, one need not worry about getting bitten as they are not functional for biting.  We have always suspected they are used for mating, however, we have never seen a photo to support that theory.

Letter 5 – Hellgrammite

 

Subject: What’s This?
Location: Winter, Wisconsn
May 29, 2012 8:38 pm
This is a weird bug that my kids and I found in Northern Wisconsin at a cabin by the Radisson Flowage. During our 3 night stay over Memorial Day weekend 2012 we found 4 of these critters running around. Please help us know what it is. Thanks
Signature: Clint Parker

Hellgrammite

Hi Clint,
This is a Hellgrammite, the larva of a Dobsonfly, and they are generally found close to water.  Hellgrammites are a favored bait for freshwater anglers.  We will be scheduling your letter to post live to our site later in the week as we will be on holiday.

Letter 6 – Hellgrammite Pupa

 

Subject: Hellgrammite pupa
Location: Black River, Springfield VT
June 22, 2012 7:48 am
Our daughter found this under a rock as she was fishing down at our local river. We love river-bugs (benthic macroinvertebrates), as I am the director of the Black River Action Team, a grassroots river group in Windsor County, in SE Vermont.
We have this pupa in a terrarium; it’s been curled up and dormant (unless disturbed, then it wriggles around energetically!) since June 14th. So far, it’s been 8 days…I’m interested to learn how long the pupal stage lasts! I understand the females live as adults just long enough to mate and then lay eggs on structures or vegetation that overhang the water — like the bridge abutments where our daughter was fishing.
Signature: Kelly Stettner, BlackRiverActionTeam.com

Hellgrammite Pupa

Hi Kelly,
We have just started getting Dobsonfly identification requests, and they generally continue until July, so we expect your Hellgrammite Pupa should metamorphose into an adult soon.  Since warmer temperatures arrive later in Vermont than in the more southern portion of the range of the Dobsonfly, you might have a slightly longer wait.  We are uncertain how long the pupal stage of the Dobsonfly lasts, but we know it is not more than a single season.  We expect that pupation takes place in spring to account for a summer emergence.

Daniel, this is great; thank you so much!  I am learning more about bugs than ever before in my life, since moving to our home on the river bank in 2010.  Lots of ID information comes from helping our state water quality lab do “bug picking” each January, but a lot comes from searching the internet and scouring your site.  Learning how the macro setting on my digital camera works has been a big help — got some awesome close-up shots of a burrowing mayfly larvae a couple of years ago!
Would you folks prefer more questions about identification, or are specific queries okay, like my question about the pupal stage of the hellgrammite?
Cheers,
Kelly

Hi again Kelly,
We would really like images of underrepresented species for our site.  We don’t have as many aquatic insects as we would prefer.  Please put the insect name in the subject line to grab our attention.  That said, all inquiries are welcomed, but we can only answer and post a few a day.

Letter 7 – Hellgrammite

 

Subject: Ugly bug
Location: North Goergia
August 27, 2012 7:39 pm
Hey my name is Kirby, and I found this thorny larvae, I’m guessing, while i was camping and never seen one before. They were every where, I didn’t kill it cause I didn’t know what it is, but I did relocate it far way from our tent.
Signature: Kirby

Hellgrammite

Hi Kirby,
We have never been able to trace the origin of the name Hellgrammite which is given to this larval Dobsonfly.  The large numbers you witnessed might be one reason the Hellgrammite is a popular bait for freshwater fishermen.

Letter 8 – Hellgrammite

 

Subject: What’s this bug?
Location: Grand River, northeastern Ohio
December 2, 2012 10:14 am
We found this bug in the shallows of the Grand River in NE Ohio in early november. Only the 1st 3 pairs of protrusions are legs, the rest are just spines. 4 inches long end-to-end.
Never seen anything like it. What is it?
Signature: Ian Griffith

Hellgrammite

Hi Ian,
The aquatic Hellgrammite, the larva of the winged Dobsonfly, is a favored bait of freshwater fishermen.

Letter 9 – Hellgrammite

 

Subject: Caterpillar type bug found
Location: Brazos River, Marlin, Tx
March 30, 2013 7:23 pm
We are in Texas and this is the second time I’ve seen one of these. It looks like a giant larvae or kind of like an earwig. It’s about 3 inches in length. I found it in shallow water under a rock on the Brazos River in Central Texas.
Signature: Scott M.

Hellgrammite
Hellgrammite

Dear Scott,
We love posting photos of Hellgrammites, the aquatic larvae of Dobsonflies.  Hellgrammites are a favorite bait for fresh water fishermen.
  We have still not been able to discover the origin of the name Hellgrammite.

Hellgrammite
Hellgrammite

Letter 10 – Hellgrammite

 

Subject: Scary…ish bug?
Location: Smithton, Pennsylvania
May 28, 2013 9:47 pm
Hi!
Today, I was walking on a trail today (a chilly 29th May) and found two of these. After numerous searches, I’m at a loss as to what these are, because I was pretty fascinated by them. The trail is in Western Pennsylvania, nearby a river. There’s lots of woods around, and lots of streams and springs, and such – if that’s helpful.
Thanks for your help!
Signature: Z

Hellgrammite
Hellgrammite

Dear Z,
This is a Hellgrammite, the larva of a Dobsonfly.  We just postdated an image of a male Dobsonfly to go live on June 5 since we will be away from the office.  We are going to postdate your Hellgrammite image to go live on June 6.

Letter 11 – Hellgrammite

 

Subject: what is this bug?
Location: west central wisconsin
May 31, 2013 4:29 am
My son found this crawling up his garage wall. He said it was about 4 inches long, with many legs, and a very sturdy body. It resembles the pictures of the water Tigers but has many more legs. They just moved into this place which is right next to a river in west central Wisconsin and they’re curious to know if they’re going to be seeing more of these kind of bugs.
Signature: bug identification

Hellgrammite
Hellgrammite

Congratulations on being introduced to a Hellgrammite.  These semiaquatic nymphs are usually found not far from water, so the river you mentioned is most likely its origin.  Hellgrammites eventually metamorphose into fearsome looking, but perfectly harmless Dobsonflies.

Letter 12 – Hellgrammite

 

Subject: river bug in Iowa
Location: Winnebago River, Mason City IA
June 9, 2013 11:32 pm
We saw several of these bugs along a river trail today after very heavy rainfall and slight flooding. Any idea what these are?
Signature: Elizabeth Haag

Hellgrammite
Hellgrammite

Hi Elizabeth,
This is a Hellgrammite, the semiaquatic larval form of a Dobsonfly.  For years, we have been trying to uncover the origin of the name Hellgrammite, but alas, our searching has not proven fruitful.  We are also hoping to eventually be able to post a photo of a pair of Dobsonflies mating.

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.

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 – Hellgrammite from California

 

Majave River
Location: Mojave River, Southern Califorina
July 4, 2011 3:40 pm
We were at the Mojave River and saw this bug in the water. It kinda looks like a larva of some sort, but in all honesty i have no idea what it is and was hoping you would be able to identify it for us.
Thanks for your time
Signature: The Green Family

Hellgrammite

Dear Green Family,
This is the larva of a Dobsonfly, commonly called a Hellgrammite.  Most of our specimens are of the Eastern Dobsonfly, though several species are known to range in California, however they are not well documented.  This is one of the Western Dobsonflies.  See BugGuide for additional information.

Letter 2 – Hellgrammite in the Snow!!!

 

snow insect
Location: mt rainier national park, washington state
February 25, 2012 2:20 am
we saw this 6 legged, spiny insect on a snowshoe in mt. rainier national park (washington) late feb 2012. from limited, ignorant research– it looks similar to firefly and lacewing larvae but not exact. wished we would have put something down there to show size-but didn’t- was at least 2 inches long. thanks
Signature: jen

Hellgrammite in the Snow

Dear Jen,
This sure looks to us like a Hellgrammite, the larva of the Dobsonfly.  Interestingly, BugGuide has a photo, also from Washington, that was posted two years ago in February.  That individual is also in the snow and there was speculation about why it was in the snow.

Thank you so much-  very nice to get an answer so quickly.  we were right next to a spring fed beaver pond with numerous geothermal springs/vents.  if that makes any difference with the strange location (snow) of a typical aquatic  bug.
Again- thanks again-
Jen

Hi Jen,
Those details might be significant, but it is still interesting that there was another Hellgrammite sighting in Washington in the snow.

Letter 3 – Hellgrammite

 

crazy ant like centipede
Location: tennessee mountains
April 9, 2012 10:13 am
this was found under a rock near a river bank, it tried to burrow into the dirt. It is spring and this was found near a cool mountain river. thanks for your time. it is about 4 nches long and maybe a half inch across the little things on its side do not move like legs..?  this bug is about 4 inches long and a half inch wide. It was found under a rock on a pebble river bank in the tennessee mountains. it’s back ”legs” dont move and it was trying to burrow under a small plant.
Signature: Heather Brannon

Hellgrammite

Hi Heather,
You are not the first person who has mistaken a Hellgrammite for a Centipede.  Hellgrammites are the larval form of Dobsonflies.  Though they are not venomous and are not considered dangerous, both immature Hellgrammites and fully grown female Dobsonflies are capable of inflicting a painful bite if carelessly handled.  Male Dobsonflies, despite their formidable looking mandibles, are not capable of biting humans.  Hellgrammites are a prized bait among freshwater anglers.

Letter 4 – Hellgrammite

 

Subject: what is this bug?
Location: Coventry,Ct
May 23, 2012 6:47 am
Mr.Bugman,what is this bug?My husband found it on a job site.It even attacked the tape messure when holding it up to it with his pinchers.
Signature: thanks sheri

Hellgrammite

Hi Sheri,
Try as we might, we have never been able to trace the origin or meaning of the name Hellgrammite, however it seems a very appropriate name for this Dobsonfly Larva.  If you think the larva is a fierce looking creature, take a peek at this adult male.  Dobsonflies and Hellgrammites are harmless, though it is possible to get a nip if the larva or adult female is carelessly handled.  The mandibles of the male are showstoppers, however, one need not worry about getting bitten as they are not functional for biting.  We have always suspected they are used for mating, however, we have never seen a photo to support that theory.

Letter 5 – Hellgrammite

 

Subject: What’s This?
Location: Winter, Wisconsn
May 29, 2012 8:38 pm
This is a weird bug that my kids and I found in Northern Wisconsin at a cabin by the Radisson Flowage. During our 3 night stay over Memorial Day weekend 2012 we found 4 of these critters running around. Please help us know what it is. Thanks
Signature: Clint Parker

Hellgrammite

Hi Clint,
This is a Hellgrammite, the larva of a Dobsonfly, and they are generally found close to water.  Hellgrammites are a favored bait for freshwater anglers.  We will be scheduling your letter to post live to our site later in the week as we will be on holiday.

Letter 6 – Hellgrammite Pupa

 

Subject: Hellgrammite pupa
Location: Black River, Springfield VT
June 22, 2012 7:48 am
Our daughter found this under a rock as she was fishing down at our local river. We love river-bugs (benthic macroinvertebrates), as I am the director of the Black River Action Team, a grassroots river group in Windsor County, in SE Vermont.
We have this pupa in a terrarium; it’s been curled up and dormant (unless disturbed, then it wriggles around energetically!) since June 14th. So far, it’s been 8 days…I’m interested to learn how long the pupal stage lasts! I understand the females live as adults just long enough to mate and then lay eggs on structures or vegetation that overhang the water — like the bridge abutments where our daughter was fishing.
Signature: Kelly Stettner, BlackRiverActionTeam.com

Hellgrammite Pupa

Hi Kelly,
We have just started getting Dobsonfly identification requests, and they generally continue until July, so we expect your Hellgrammite Pupa should metamorphose into an adult soon.  Since warmer temperatures arrive later in Vermont than in the more southern portion of the range of the Dobsonfly, you might have a slightly longer wait.  We are uncertain how long the pupal stage of the Dobsonfly lasts, but we know it is not more than a single season.  We expect that pupation takes place in spring to account for a summer emergence.

Daniel, this is great; thank you so much!  I am learning more about bugs than ever before in my life, since moving to our home on the river bank in 2010.  Lots of ID information comes from helping our state water quality lab do “bug picking” each January, but a lot comes from searching the internet and scouring your site.  Learning how the macro setting on my digital camera works has been a big help — got some awesome close-up shots of a burrowing mayfly larvae a couple of years ago!
Would you folks prefer more questions about identification, or are specific queries okay, like my question about the pupal stage of the hellgrammite?
Cheers,
Kelly

Hi again Kelly,
We would really like images of underrepresented species for our site.  We don’t have as many aquatic insects as we would prefer.  Please put the insect name in the subject line to grab our attention.  That said, all inquiries are welcomed, but we can only answer and post a few a day.

Letter 7 – Hellgrammite

 

Subject: Ugly bug
Location: North Goergia
August 27, 2012 7:39 pm
Hey my name is Kirby, and I found this thorny larvae, I’m guessing, while i was camping and never seen one before. They were every where, I didn’t kill it cause I didn’t know what it is, but I did relocate it far way from our tent.
Signature: Kirby

Hellgrammite

Hi Kirby,
We have never been able to trace the origin of the name Hellgrammite which is given to this larval Dobsonfly.  The large numbers you witnessed might be one reason the Hellgrammite is a popular bait for freshwater fishermen.

Letter 8 – Hellgrammite

 

Subject: What’s this bug?
Location: Grand River, northeastern Ohio
December 2, 2012 10:14 am
We found this bug in the shallows of the Grand River in NE Ohio in early november. Only the 1st 3 pairs of protrusions are legs, the rest are just spines. 4 inches long end-to-end.
Never seen anything like it. What is it?
Signature: Ian Griffith

Hellgrammite

Hi Ian,
The aquatic Hellgrammite, the larva of the winged Dobsonfly, is a favored bait of freshwater fishermen.

Letter 9 – Hellgrammite

 

Subject: Caterpillar type bug found
Location: Brazos River, Marlin, Tx
March 30, 2013 7:23 pm
We are in Texas and this is the second time I’ve seen one of these. It looks like a giant larvae or kind of like an earwig. It’s about 3 inches in length. I found it in shallow water under a rock on the Brazos River in Central Texas.
Signature: Scott M.

Hellgrammite
Hellgrammite

Dear Scott,
We love posting photos of Hellgrammites, the aquatic larvae of Dobsonflies.  Hellgrammites are a favorite bait for fresh water fishermen.
  We have still not been able to discover the origin of the name Hellgrammite.

Hellgrammite
Hellgrammite

Letter 10 – Hellgrammite

 

Subject: Scary…ish bug?
Location: Smithton, Pennsylvania
May 28, 2013 9:47 pm
Hi!
Today, I was walking on a trail today (a chilly 29th May) and found two of these. After numerous searches, I’m at a loss as to what these are, because I was pretty fascinated by them. The trail is in Western Pennsylvania, nearby a river. There’s lots of woods around, and lots of streams and springs, and such – if that’s helpful.
Thanks for your help!
Signature: Z

Hellgrammite
Hellgrammite

Dear Z,
This is a Hellgrammite, the larva of a Dobsonfly.  We just postdated an image of a male Dobsonfly to go live on June 5 since we will be away from the office.  We are going to postdate your Hellgrammite image to go live on June 6.

Letter 11 – Hellgrammite

 

Subject: what is this bug?
Location: west central wisconsin
May 31, 2013 4:29 am
My son found this crawling up his garage wall. He said it was about 4 inches long, with many legs, and a very sturdy body. It resembles the pictures of the water Tigers but has many more legs. They just moved into this place which is right next to a river in west central Wisconsin and they’re curious to know if they’re going to be seeing more of these kind of bugs.
Signature: bug identification

Hellgrammite
Hellgrammite

Congratulations on being introduced to a Hellgrammite.  These semiaquatic nymphs are usually found not far from water, so the river you mentioned is most likely its origin.  Hellgrammites eventually metamorphose into fearsome looking, but perfectly harmless Dobsonflies.

Letter 12 – Hellgrammite

 

Subject: river bug in Iowa
Location: Winnebago River, Mason City IA
June 9, 2013 11:32 pm
We saw several of these bugs along a river trail today after very heavy rainfall and slight flooding. Any idea what these are?
Signature: Elizabeth Haag

Hellgrammite
Hellgrammite

Hi Elizabeth,
This is a Hellgrammite, the semiaquatic larval form of a Dobsonfly.  For years, we have been trying to uncover the origin of the name Hellgrammite, but alas, our searching has not proven fruitful.  We are also hoping to eventually be able to post a photo of a pair of Dobsonflies mating.

Letter 13 – Hellgrammite

 

Subject: What is it?
Location: Rhode Island
June 8, 2014 6:08 pm
We found this crawling on our sidewalk in northern Rhode Island. There appeared to be the shells of others around. It was found in the middle of May on a mild spring day. What is it?
Signature: Any

Hellgrammite
Hellgrammite

Dear Any,
This impressive creature is a Hellgrammite, the larva of a Dobsonfly, and they are generally found near a source of water.

Letter 14 – Hellgrammite

 

Subject: what is this bug?
Location: Milford nh 03055
May 11, 2015 1:24 am
My husband and I went to the store this morning and noticed this large and honestly creepy bug… what is it?
Signature: The Guinesso’s

Hellgrammite
Hellgrammite

Dear Mrs. Guinesso
This memorable insect is a Hellgrammite, the larva of a Dobsonfly, and they are generally found near water.  Hellgrammites are a favorite bait of freshwater anglers.  If this Hellgrammite creeped you out, you should be thankful you did not see a winged adult male Dobsonfly.  Despite his fearsome appearance, he is perfectly harmless.

Letter 15 – Hellgrammite

 

Subject: What’s the name of this bug?
Location: Stamford, Connecticut
May 16, 2015 11:24 am
Can’t find anything online !! A few things I know: It comes out when it rains. It has huge wings and it has a stinger.
Signature: Thalita

Hellgrammite
Hellgrammite

Dear Thalita,
This is a Hellgrammite, the larval form of a Dobsonfly.  When it matures into a winged adult, it is quite fierce looking, and the adults are sexually dimorphic.  Male Dobsonflies have enormous sickle shaped mandibles, and despite the fierce appearance, they are harmless.  Female Dobsonflies have much smaller, though more utilitarian mandibles that can be used to defend her against predators.  We recently learned first hand what we have long suspected, that the bite of a female Dobsonfly might draw blood.  You are misinformed about Dobsonflies or Hellgrammites possessing stingers.

Letter 16 – Dessicated Hellgrammite

 

Subject: Long black bug with pinchers?
Location: Hudson valley, ny
June 5, 2015 10:24 am
Hi.
I found this bug dead in an abandoned farmhouse in central new york in late may. The underside was a an orangey-brown color and I’ve never seen a bug like this in that area before. At first I thought it was a queen termite or something, vit that doesn’t seem to be the case. Do you guys have any clue to what this is?
Signature: – its very scary pls help

Hellgrammite
Hellgrammite

We are speculating that the farmhouse was near a stream or river.  This is a dessicated Hellgrammite, the larva of a Dobsonfly.  Both Hellgrammites and female Dobsonflies are known to bite, and they may draw blood with their powerful mandibles, but they are considered harmless, and Hellgrammites are prized bait for freshwater anglers.

Letter 17 – Hellgrammite

 

Subject: Found at south Carolina lake house
Location: South Carolina
April 3, 2016 5:19 pm
I found this in the driveway of my parent’s home in South south Carolina. It’s very slow and about 5 inches long. It’s head is flat with large pincers. The front half looks like a beetle, hard segments, 6 segmented legs. The rest looks like a centipede. It has multiple segments with what seem like non functioning legs.
Signature: Curious in Carolina

Hellgrammite
Hellgrammite

Dear Curious,
Though we have never been able to identify successfully the etymological origin of the word Hellgrammite, it is nonetheless an appropriate name for the impressive larva of the Dobsonfly.  While five inches seems like a bit of an exaggeration, Hellgrammites are large insects.  Hellgrammites are found near sources of water since they are aquatic, but they will move to drier ground to pupate.  Adult Dobsonflies should begin to appear in your area very soon.

Letter 18 – Hellgrammite

 

Subject: Satan’s spawn
Location: Northern Maine
May 29, 2016 6:34 pm
Any idea what this could be? Was in northern Maine near The Forks and river. Quite a few around. Bleeeeeech!
Signature: Nanci “I’m not touching that” Sullivan

Hellgrammite
Hellgrammite

Dear Nanci,
This is the larva of a Dobsonfly, and we are very amused at your subject line because Dobsonfly Larvae are known as Hellgrammites, and we have never to our satisfaction been able to determine the etymology of that name, which might actually mean “Satan’s Spawn.”  Though they are not considered dangerous, Hellgrammites can deliver a painful pinch that might even draw blood in some instances.  Hellgrammites are a prized bait for freshwater fishermen.

Letter 19 – Western Hellgrammite, we believe

 

Subject:  Underwater centipede??
Geographic location of the bug:  Alta, CA
Date: 12/08/2017
Time: 12:29 AM EDT
So, our house wraps around the remnants of a historic gold mine with access to the mine from a back door. There is a fresh water spring that flows from miles back, with several small, dammed pools about a quarter mile in. Today while spelunking, we crossed the path of a peculiar centipede looking insect below the water in a pool about 8 to 10 inches deep! He had a sort of swim/crawl movement and I’d say about 3 inches long and a half inch thick. Wondering if he’s a native ethereal dweller or some sort of astral crosser come to us from The Upsidedown.
How you want your letter signed:  the good people of InnerEarth

Aquatic Larva, probably Dobsonfly

Dear good people of InnerEarth,
This is an aquatic larva of a flying insect, and we are relatively certain it is a member of the family Corydalidae, which includes Dobsonflies and Fishflies.  The similar looking larva of the Eastern Dobsonfly is known as a Hellgrammite.  Here is a BugGuide image of a Fishfly larva.  Your larva might be that of a California Dobsonfly,
Neohermes californicus

 

Letter 20 – Hellgrammite

 

Subject:  Big weird bug
Geographic location of the bug:  Rhode Island
Date: 06/02/2018
Time: 08:24 AM EDT
Your letter to the bugman:  Please tell me what this thing is because I am terrified
How you want your letter signed:  Enrique

Hellgrammite

Dear Enrique,
This is a Hellgrammite, the larval form of the Dobsonfly.  Both adults and larvae are quite fierce looking, but they have no venom and they are harmless to humans, though female Dobsonflies and Hellgrammites have powerful mandibles that might deliver a painful pinch.  Freshwater fishermen often use Hellgrammites for bait.

Thanks man! That’s crazy, when I saw it I had no idea what it was lol

Letter 21 – Hellgrammite

 

Subject:  Bug indentification
Geographic location of the bug:  Georgia
Date: 05/06/2019
Time: 10:04 PM EDT
Your letter to the bugman:  Seen on a river bank in eastern central Georgia
How you want your letter signed:  Thanks, Randy

Hellgrammite

Dear Randy,
We love Hellgrammites, the aquatic larvae of the winged Dobsonfly.

We saw this on a fishing trip with my son. Thank you SO much for helping us identify it!!!

Letter 22 – Hellgrammite

 

Subject:  Prehistoric looking bug
Geographic location of the bug:  Southwestern PA
Date: 06/27/2019
Time: 01:25 AM EDT
Your letter to the bugman:  I was fishing a larger river and went up to the road and noticed these bugs all over the place. They were smashed on the road and were trying to cross the road, from river bank to cornfield and vise versa. The bugs were between 3 and 7 inches long.
How you want your letter signed:  Joey

Hellgrammite

Hi Joey,
Did you catch many fish?  If not, nature provided you with an excellent bounty to change your luck.  The Hellgrammite, the larval form of the Dobsonfly, is a prized bait among freshwater anglers.

I knew they looked like hellgramites, but I didnt know they ventured out of the water like they did. Cool thank you for the quick reply.

We believe they leave the water to pupate.

Hellgrammite

 

Hellgrammite

 

Subject:

 

 

 

Authors

  • 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.

    View all posts
  • 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.

    View all posts
Tags: Dobsonflies

Related Posts

18 Comments. Leave new

  • I used to love looking for these in the ditch when I was a kid (I lived in a very rural marshy area in VT) but I never knew they were Dobsonfly larvae! I did know they were called Hellgrammites though. Glad to know more about them almost 20 years later 🙂

    Reply
  • Looks like the bug Khan used against the Enterprise crew!

    Reply
  • haha it reminds me of “the tingler.” http://goregirl.files.wordpress.com/2011/05/the-tingler3.jpg

    Reply
  • Please send more!

    Reply
    • I found one of those today in a river in Central Ky. I didn’t know what it was but wasn’t about to grab it with those jaws lol.

      Reply
  • these things creep me out something fierce

    Reply
  • My skin crawls just looking at this thing. The only way I’d get a picture like that is if I had a 100x zoom on my camera! What it changes into is even creepier! Thanks for creeping me out for the day!

    Reply
  • Joseph Clarke
    July 20, 2014 8:26 pm

    I found one in Conway Mo July 19, 2014. It was in the river down the street from my house and it got on my nephews shorts.

    Reply
  • Do you sell live hellgrammites for fishing

    Reply
  • ProjectScaliber
    June 23, 2017 6:57 am

    This past month I caught a bunch of hellgrammites by my work site in Moreno Valley, Riverside County of Southern California, I found a interesting trait as they are cannibalistic, and some carry a Barb on the tail like that of a hookworm

    Reply
  • Thomas R Miller
    March 30, 2019 7:36 pm

    Growing up in the hills of West Central PA near Hollidaysburg and loving to fish, I found it a delight to walk the edge of streams and catch (what locals called) soft shelled crabs (crayfish) for bass bait. It was in doing that that I was introduced to lifting rocks in fast moving shallow water and finding, what to me, became the best bait for catching crappies, etc. – the hellgrammite. They were tough and you could catch quite a few fish on one bait if you played the game just right. If you try it, one thing you’ll learn early on is those tweezers can inflict a bite that will bring blood but you learn quickly and the pain is short lived. A second thing you’ll learn is that the hellgrammite moves backward more than he’ll go forward; so, you’ve got to be quick in retrieving him from the rock. A third lesson to note – the hellgrammite has 4 little hairlike “feelers” at the tail end. That little critter has a lot of life remaining in him after your hook is slipped under the shell that surrounds the body behind the head (That’s how I put it on the hook for bait). You’ve got to use your finger nails to pitch those little hairs off or sure-a-shootin’ he’ll take your hook under a rock if one is available. If you’ve never tried it before, go lookin’, catch yourself a hand full (recommend having a pail with you- more than 1 in your hand can be a problem) and have fun fishing.

    Reply
  • I have went up the Sacramento river, above the damn. I was with both of my brother’s, Steve & Johnny. Before going down to the river we asked the guy in the store if anyone was catching any fish? He told us that no one was catching anything, nothing hopeful. My brother Steve was looking under rocks for helgies. We all started looking and before long we had quite a few. The first cast nailed a 3lb rainbow. We had a blast, I can’t remember if we caught 12 or 14 trout, ( all good sized fish )!! We went back to the store and showed the guy the fish. He couldn’t believe that we had just caught those in the river. He asked where we got em’? I asked myself, “where does he think we got them?” My brother Steve answered him by saying, “in the water” I’ll never forget that day or the Hellgrammite’s!!!

    Reply
    • Awesome story. Doesn’t the store owner know that fishermen are notoriously protective of their best fishing spots?

      Reply
  • The North Fork of the Navarro River is a great place to find them in the spring and summer.

    Reply

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