Dobsonfly Bite: Anatomy, Symptoms, and Treatment

Dobsonflies are large, fearsome-looking insects, so if you have spotted one around your house, here’s everything you need to know about the Dobsonfly bite.

The Dobsonfly is one of the largest insects in the world (males can grow up to five inches long), and has a menacing look enough to scare even the most ardent of insect lovers.

This insect is found all across North America, but it’s really the larvae of the Dobsonfly, who you are likely to meet more because the adults hardly live for about a week.

Their larvae are called hellgrammites, and these are aquatic insects that hide under rocks in rapid waters. They are equally hellish-looking creatures.

But their aggressive features belie a simple fact: these bugs are not dangerous to humans. And if you have come here to understand the ill effects of their bite, let us say upfront that there are none.

But let’s talk a bit more about Dobsonfly, their unique features that make them look like something from a horror movie, and why those features have nothing to do with biting.

What Do They Look Like?

Perhaps the key reason behind the notoriety of the Dobsonfly is how they look.

The males sport large, one-inch sickle-shaped mouthparts in front, which look like tentacles. They also have two long antennae spread perpendicular to their bodies.

These long mouthparts are actually not as dangerous as they look – they are not very useful for fighting because they lack leverage.

Their real purpose is not to fight; they are useful during mating. The male grabs the female with these long mouthparts during sex.

Female dobsonflies have short but sharp protruding jaws. These are actually more dangerous because they can bite. The bites are quite painful.

Both the male and female have large veined wings that cover their entire bodies and are slightly overlapping in the middle when closed. Both are taupe-colored insects, and they have small white dots on their wings.

Dobsonfly Bite: All You Need To Know

What Do Their Larvae Look Like?

Dobsonflies spend most of their lives as larvae, and these larvae (called hellgrammites) are aquatic. They live in rivers and hide under rocks.

Hellgrammites look like flattened centipedes and are usually colored either black, brown, or tan so that they can easily hide against the rocky background.

Hellgrammites have their own set of pincers, and just like the female Dobsonfly, they are painful biters.

They have three pairs of legs on the thorax and eight pairs of appendages on each side (which look like more legs). These appendages have a hairy tuft at the bottom.

Hellgrammites have adapted to their environment of rapidly moving waters by developing another hooked appendage at the tip, which acts like a claw to prevent them from getting swept up in a strong current.

Are Dobsonflies Dangerous?

Dobsonflies are not particularly dangerous to humans, and at least the adult dobsonfly male does not bite.

Adult females can bite, and so can their larvae, the aptly named “hellgrammites.” Both their bites can be painful. But on the whole, these bugs are quite harmless to us.

Dobsonfly Bite: All You Need To Know

Dangerous To Other Insects

Dobsonflies begin their lives as aquatic creatures, and their larvae are one of the most voracious predators of insects found in their surroundings.

They are quite large, anywhere between two to three inches in length. But what’s more, is that they are not afraid of attacking anything – they even eat up small fish!

You will find these larvae in those parts of rivers that are near the mountains, or at least in sloping plains where the river runs very fast. Hellgrammites often hide under rocks in these bodies of water.

They use their hiding pace to their advantage, snatching up unsuspecting prey as it floats past them. They also hide from predators such as bass under these rocks.

Dangerous To Humans

If you look at the physical characteristics of the male and the female Dobsonfly, you might be forgiven for thinking that the male is more menacing.

Males have long (up to an inch!), fleshy mandibles protruding from their mouths, giving the impression of elephant tusks ready to impale anyone trying to hurt them.

But these large mandibles are pretty much useless in a fight because they can’t bite anything!

Females have short, sharp mandibles, and those do bite. If you try to place a female on your hand, get ready for a swift and sharp pincer attack.

Dobsonfly Bite: All You Need To Know

It is best not to mess around with the females because their painful bites would leave you with a big rash.

Lastly, when you are in and around water, try to stay away from rocks. Hellgrammites can bite just as well as the Mumma dobsonflies, and the pain isn’t any lesser.

Their bites can pierce the skin and cause minor bleeding, so if you get bitten, you should thoroughly wash the wound and apply some antiseptic to it.

Should you be worried about meeting dobsonflies?

Your chances of meeting a real Dobsonfly are actually quite bleak; if anything, you should beware of their larval stage, the hellgrammites.

Dobsonfly life cycles are quite inverted – they live two or three years as larvae, but when they finally emerge as adults, they only have about a week left to live.

The purpose of a Dobsonfly’s life is actually just to mate – they don’t even eat for their short time on earth. They just mate and then lay eggs so that the next generation can continue living.

You will only find Dobsonfly near your home if there is a source of rapid waters running nearby, like a river.

They are nocturnal creatures and are attracted to light, so if you leave the outdoor lights on, you might find some of them flying around.

Dobsonfly: Are They Poisonous?

No, dobsonflies are not poisonous or venomous. As we said earlier, the females and larvae of the species can bite if you attack or try to handle them. But apart from that, they don’t cause us any harm.

How Do Dobsonflies Attack?

Simply put: they don’t attack humans. Dobsonflies are not interested in humans or biting or drawing blood or anything like that.

After all, if you only have a week to live, would you be interested in fighting creatures fifteen times your size? Their entire purpose in life is to mate and reproduce.

If you try to handle a female Dobsonfly roughly or place it on your hand, it might bite. But honestly – it is you who are to blame in that situation!

How Do Dobsonflies Fight?

Many people think that the large, sickle-shaped pincers at the front of the male Dobsonfly’s mouth are meant for fighting other flies.

The truth is these large mandibles are not useful in a fight except as a defense mechanism.

Moreover, the flies don’t fight each other over food or resources – they fight to win over the ladies.

The male Dobsonfly’s mandibles are actually evolved to attract females – as in, gee look, what big mandibles that guy has!

Females tend to pick the ones with the bigger mandibles. Unfortunately, size does matter even in the insect world, folks.

Wrap Up

Dobsonflies are harmless creatures, and as long as you don’t go around poking your hand in their face, they are not going to come and bite you.

In fact, a Dobsonfly sighting is a bit of a unicorn because these bugs hardly live for 3-7 days. If you live near a running stream and keep bright lights on at night, you might see some of them.

Thank you for reading!


  • 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.

    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

6 thoughts on “Dobsonfly Bite: Anatomy, Symptoms, and Treatment”

  1. I thank you for your pictures as I recently came across one of this unusual looking creatures. Been Trying to identify it with no luck till coming across this site and your post. I have never seen one of these before and have lived here all my life. Rather an interesting insect for sure.

  2. Love this website. Spent my childhood terrified of bugs especially big ones! Now much older, wiser and in awe of nature, I love finding and/or learning more about insects ? I saw a Dobson Fly about 6 yrs ago in my backyard in NY. I believe it was a male. Wish I had known it wouldn’t sting . I might have gotten a little closer. Now living in Virginia where there are beautiful varieties of dragonflies. My favorite thought is that each insect has an individual personality. Talk about diversity!


Leave a Comment