10 Dobsonfly Interesting Facts (And Their Larvae Too)

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,

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 for the great photo Bob.

Letter 4 – Dobsonflies and Fishflies


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!
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.

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