What Do Giant Water Bugs Eat: A Quick Guide for the Curious

Giant water bugs are fascinating creatures that live in ponds and ditches, capturing the attention of both scientists and casual observers alike. Being the largest among the Heteroptera, these predators can reach up to 4 inches in length in some species found in South America source. But, have you ever wondered what these impressive insects eat?

As a carnivorous insect, the giant water bug primarily feeds on other aquatic animals. Their diet consists of various prey, such as small fish, tadpoles, and even other insects. Using their strong forelegs, they seize their prey and inject a powerful venom, which helps to subdue and digest the victim.

So, if you ever come across a giant water bug in its natural habitat, now you know what it’s searching for in the water. These voracious predators play a crucial role in their ecosystem, helping to keep the populations of other aquatic creatures in check.

General Overview of Giant Water Bugs

Giant water bugs, belonging to the Belostomatidae family, are fascinating aquatic insects known for their predatory nature. Found in various freshwater habitats, they are considered true bugs and are among the largest insects in the world. One well-known species is Lethocerus americanus, which can grow up to 2-3 inches in length.

As a predatory insect, giant water bugs have unique adaptations to help them catch their prey. Their front legs are shaped like pincers, allowing them to seize and hold their victims. Swimming abilities are also enhanced by their flattened rear legs, which are equipped with tiny hairs that aid in propulsion through water.

These large bugs are part of the Hemiptera order, and their family includes various genera such as Lethocerus, Belostoma, and Abedus. Some of their key characteristics include:

  • Dark brown coloration
  • Oval-shaped, flattened body
  • Pincer-like front legs
  • Oar-like rear legs for swimming

A comparison of two notable species, Lethocerus americanus and Lethocerus indicus, reveals similarities and differences:

Feature Lethocerus americanus Lethocerus indicus
Size Up to 2-3 inches Up to 4 inches
Habitat North America South and Southeast Asia
Common Name Giant water bug Giant water scorpion

Now you have a better understanding of giant water bugs, including their predatory nature, unique characteristics, and differences between species. Remember, these are fascinating creatures that play an essential role in aquatic ecosystems as predators, controlling populations of other insects and small aquatic animals.

Giant Water Bugs’ Diet

Giant water bugs are known as predatory insects that primarily feed on a diverse range of aquatic organisms. Some of their favorite prey items include:

  • Small fish
  • Tadpoles
  • Crustaceans
  • Snails
  • Mosquito larvae

These bugs can efficiently catch their prey with their piercing-sucking mouthparts, which make them effective hunters in their aquatic environments. For example, they can snatch up unsuspecting small fish to fulfill their dietary needs.

In addition to their diverse diet, giant water bugs exhibit remarkable adaptability. They are not very picky eaters and can adjust their preferences based on the availability of prey in their habitat. This trait makes them successful predators in a variety of aquatic ecosystems.

Their Predators and Defense Mechanisms

Giant water bugs, despite being predators themselves, also face threats from other organisms. Some of their common predators include:

  • Turtles
  • Snakes
  • Birds
  • Bullfrogs
  • Ducks

To protect themselves from these predators, giant water bugs rely on a combination of physical and behavioral adaptations.

One of the most notable defenses they possess is their large and powerful pincers, which they use to not only capture prey but also to fend off potential threats. Their bites are known to be painful and can earn them the nickname of “toe-biter” or “toe biter” due to their nature of biting when they feel threatened or cornered.

In addition to their pincers, giant water bugs also employ camouflage to blend in with their surroundings. Their dark brown color and oval shape allow them to remain inconspicuous among rocks, vegetation, and within the water.

To further evade detection, these insects can stay motionless for extended periods, avoiding reactions from predators who rely on movement to identify prey. This behavior, coupled with their stealthy appearance, helps them stay out of harm’s way.

So, when you encounter a giant water bug, remember that they have a few tricks up their sleeves to stay safe from predators, just like those they prey upon.

Habitat and Distribution

Giant water bugs inhabit various freshwater habitats across different regions of the world. In North America, they are commonly found in the United States and Canada. Their range extends to Southeast Asia and South America as well.

You can spot these aquatic insects in environments such as ponds, lakes, streams, wetlands, and marshes. They thrive in areas with abundant vegetation, which offers them ample hiding spots and hunting grounds for their prey.

In some cases, you may even discover giant water bugs in residential areas, especially if there are bodies of water nearby. These adaptable insects make the most of the available freshwater habitats, allowing them to thrive in various ecological settings.

Some key aspects of their habitat include:

  • Abundant vegetation for hiding and hunting
  • Freshwater environments like ponds, lakes, and streams
  • Diverse distribution across North America, Southeast Asia, and South America

Remember to be cautious if you wade in water where giant water bugs reside. They can deliver a painful bite if accidentally disturbed. Overall, understanding their habitat preferences can help you appreciate these fascinating creatures and stay safe around them.

Adaptations and Characteristics

The giant water bug is an impressive predator with various unique adaptations that help it succeed in its aquatic environment. Let’s examine some of its characteristics:

  • Body: They have a flattened, oval-shaped body allowing them to move efficiently through water and hide from potential predators.
  • Head: Their head is equipped with strong, piercing-sucking mouthparts called a beak or proboscis, which they use to grasp and inject digestive enzymes into their prey.

Not only are the head features essential, but their appendages play a vital role in their survival as well:

  • Front Legs: Giant water bugs have large, powerful front legs armed with sharp claws, which are perfect for capturing and holding onto prey.
  • Wings: They possess wings that enable them to fly between water sources and escape from threats.
  • Antennae: Equipped with long, thin antennae, these bugs can sense their environment and locate potential food sources.

Breathing and respiration are crucial to the giant water bug’s existence:

  • Spiracles: Spiracles are small openings on the sides of their abdomen that help them breathe underwater.
  • Snorkel: They use a special snorkel-like breathing tube or siphon that extends from the tip of their abdomen to take in air from the water surface.

In summary, giant water bugs have several unique adaptations and characteristics, from their powerful front legs to their specialized breathing apparatus. These features equip them for a successful life as formidable aquatic predators, allowing them to thrive in their natural environment.

Reproduction and Life Cycle

Giant water bugs have an interesting life cycle! They go through several stages, starting as eggs and progressing into nymphs before becoming adults. Let’s explore each stage and see how these fascinating creatures develop.


  • The female lays her eggs on a submerged plant or other underwater surface.
  • Eggs typically hatch in about one to two weeks, depending on the temperature.


  • Upon hatching, these bugs are called nymphs and look like smaller versions of the adult.
  • They will molt several times during the summer, growing slightly larger each time.
  • Nymphs are already strong predators, hunting small aquatic creatures to feed on.
  • After four to five molts, the nymph will become an adult.


  • The entire life cycle takes place during the warm summer months.
  • Adult giant water bugs remain active and continue preying on various aquatic animals.
  • They have strong wings, which allow them to fly from one water source to another in search of food.
  • During this period, mating occurs, and females lay their eggs, starting the cycle anew.

Overall, giant water bugs have a fascinating life cycle, starting as eggs, growing into predatory nymphs, and finally becoming adults. Remember, these creatures undergo several transformations during the summer months as they journey through life.

Role of Giant Water Bugs in Ecosystem

Giant water bugs play a crucial role in maintaining the balance of aquatic ecosystems. They are predatory insects and help control populations of various small aquatic creatures.

For instance, these bugs feed on mosquito larvae, helping reduce the spread of diseases like malaria and dengue transmitted by mosquitoes. By preying on mosquito larvae, they help keep their numbers in check.

In addition to mosquito larvae, they also consume:

  • Small fish
  • Frogs
  • Tadpoles
  • Snails
  • Aquatic insects

By controlling the populations of these small creatures, they indirectly aid in preserving aquatic plants and algae from overgrazing. In this way, they help maintain the diversity of plant and animal life in their habitats.

As a result, other animals also depend on them for their survival. For example, giant water bugs serve as prey for:

  • Fish
  • Birds
  • Turtles

Their presence can also indicate the health of aquatic ecosystems. If their populations decline, it might signify an imbalance in the food web or water pollution.

In summary, giant water bugs contribute significantly to the stability of aquatic ecosystems by feeding on various aquatic creatures, controlling their populations, and serving as prey for other animals.

Giant Water Bugs as a Delicacy

Giant water bugs are not only interesting aquatic insects but have been considered a delicacy in some parts of the world. In Asia, for instance, they are consumed in various forms, such as raw, boiled, or fried. As these insects can grow quite large, they offer a substantial source of protein and flavor.

When it comes to culinary uses, you can find giant water bugs in a range of dishes, including salads or delicious stir-fries. Folks in this region of the world appreciate their unique taste and texture while savoring the insects in their meals.

In local markets, giant water bugs can be found for sale, making them accessible to consumers who want to try this delicacy. These insects, known scientifically as Lethocerus, are available in various preparations and are often bought by adventurous eaters looking for a unique gastronomic experience.

Below are some typical ways in which giant water bugs are served:

  • Raw: Served uncooked, often as a topping or ingredient in salads.
  • Boiled: Cooked briefly in boiling water, retaining their texture and flavor.
  • Fried: Deep-fried or pan-fried, giving them a crispy outer layer and a tender inside.

So, if you are an adventurous foodie and have the opportunity to try giant water bugs, don’t hesitate to sample this unique, protein-rich delicacy. While it may not be everyone’s cup of tea, you might just find a new and exciting culinary experience awaiting you.

Human Interactions and Impact

Giant water bugs might occasionally find their way into your backyard, especially if you live near freshwater sources like ponds or streams. They are attracted to porch lights at night due to their natural instinct to hunt for prey near the water’s surface, which usually reflects moonlight.

  • Porch lights lure them from their natural habitats, and they might end up in your pool or garden.

Water pollution is a concern for these insects as it negatively impacts their prey availability and their reproductive abilities. Contaminated water can lead to a decline in the population of giant water bugs and disrupt the natural balance of the ecosystem.

  • Polluted water affects their food sources and breeding patterns.
  • A decrease in their population can impact the ecosystem.

Some people might experience an allergic reaction if bitten by a giant water bug. Although their bites are not venomous, they can be quite painful due to the strong mandibles used to inject digestive enzymes into their prey.

  • Be cautious when handling them or when they are in your vicinity.
  • Seek medical attention if you experience severe pain or an allergic reaction.

To summarize, giant water bugs can impact your backyard environment and, in turn, be affected by human activities such as pollution and artificial lighting. While they generally don’t pose a significant threat to humans, it’s essential to be cautious if you come across one.

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 – Giant Water Bug


Subject: What is this?
Location: Central Oklahoma
August 13, 2015 6:06 am
I found this at work. I live in central Oklahoma. It is slightly over 3″ long, moves very quickly, and uses its antenna looking things to help it walk. The pointed thing on its rear appears to retract when it runs.
Signature: F. Black

Giant Water Bug
Giant Water Bug

Dear F. Black,
This is a Giant Water Bug, commonly called a Toe-Biter, and it is an aquatic predator capable of flying from pond to pond.  They are attracted to light, which might explain why you found it at work.  Like other True Bugs, their mouths are adapted to pierce and suck fluids from the bodies of their prey, and they are reported to deliver a painful, but not dangerous bite, if carelessly handled or accidentally encountered while swimming or wading.

Letter 2 – Giant Water Bug


toe biter
Thanks to your site I was able to identify this bug as a toe biter. I’ve lived in northeastern CT for nearly 40 years and have never seen one of these big guys before. My kids were afraid to go to bed! LOL Thanks!

Hi Rob,
Thanks for your photos. We hope you don’t use this Toe-Biter as an April Fool’s joke today.

Letter 3 – Giant Water Bug


I’m really glad I found your site. I’m writing to tell you we found this bug on our sliding door one Saturday night. We live in Sunderland, Ontario. We have 2 man made ponds and all the goldfish died this year. We can’t figure out why. Could this bug have killed all our fish? Thanks for any help you can give us!!!
Colleen Cassidy

Hi Colleen,
Toebiters will not be able to kill large koi, but small goldfish are easy game.

Letter 4 – Giant Water Bug


What’s this bug called?
This huge bug literally fell from the sky, bounced off my car and landed at my feet. I never saw it fly so I am guessing it was dropped by a bird – lunch lost! It is a bit longer than 2" and was trying to quickly scurry away. I took a few pics when it calmed down after a few minutes. I was in the village of Madoc, Ontario, Canada in early September when I took the pictures. Could you please tell me what this monster may be?
Best regards,
Jeff Scott

Hi Jeff,
This is a Giant Water Bug also known as a Toe-Biter. They are the largest True Bugs in North America and can deliver a painful bite. They can fly as well as they can swim to to their aerodynamic build, and it probably did just attempt a sloppy landing as they are very clumsy on dry land.

Letter 5 – Giant Water Bug


Giant Water Bug
Mon, Oct 27, 2008 at 12:34 AM
Hi, love this site. I have one here I found in a small local pond, among other water insects. It appears to be a giant water bug. I have looked throughout the site and seen several varieties. It still has no wings, and surfaces to attach a bubble to its sternum before diving back down to the bottom of the aquarium. I am feeding it moths and flies, observed it and other beetles feeding on floating bee remains. Will it eventually crawl out and scare the fiber out of my girlfriend?
thank you
Soledad, CA

immature Giant Water Bug
immature Giant Water Bug

Hi Lanz,
There are three genera of Giant Water Bugs and all three grow wings as adults and can fly.  When it matures, your specimen may decide your aquarium doesn’t suit its needs and it may try to fly away.  Your specimen is either Abedus or Belostoma.  We will try to get some assistance on which genus your specimen belongs to.

immature Giant Water Bug
immature Giant Water Bug

Letter 6 – Giant Water Bug


Huge Roach-like bug; Large eyes
July 8, 2010
Hello. I found this very large bug slowly working it’s way down the hallway of our building, in Tampa FL.
It seems to be slowly dying, or maybe just really sleepy, as it is not moving very much, and only slowly when startled.
It looks like a roach in shape, but it has large eyes, and a pointed nose(?) that goes down it’s underside, and no antennea. Unless they broke off before I saw them. It also has very large front legs. The back legs are wide and flat. It is brown/green in color, with stripes on it’s underside. It’s so big I can actually see when it takes a breath. It measures 2.5″ in length.
Please let me know what you think this bug is.
Thank you for your time!
Tampa, FL


Just posted bug for ID, but found it in UC
July 8, 2010
Hello again,
I just sent you some pic’s of a large roach like bug with large eyes. In fact, I think the subject line was very close to that…
Anyway, after submitting my bug, I happened to look at your Unnecessary Carnage page, and happened upon the same bug I found. It turned out to be a Giant Water Bug (Belostomatidae).
The reason I am writing you back is to inform you that after I found out what he was, I proceded to take him outside to the run-off ditch, and put him in the water. He definitely perked up after that! I also noticed the over-abundance of tadpoles that were swimming around in the ditch, and have no doubt he’ll be feasting on some of them in due time.
No unnecessary carnage here today!
Keep up the great work!


Hi Steve,
Were it not for your wonderful followup report, we probably would have just provided you with an answer and not posted your letter.  Thanks for taking the time to research your Giant Water Bug.  They are quite clumsy on land, but in the air or in water they are quite streamlined.

Letter 7 – Giant Water Bug


I’m not sure this is native to the United States
Location: Baltimore, MD (but I’m not sure its domestic)
April 22, 2011 9:05 am
I was recently at work and happened to look down when I was leaving. On the ground and on its back it kind of looked like a large beetle, but I flipped it over and it definitely wasn’t a beetle. It was about 4-5” in length and didn’t move around even though it was alive. I’ve tried to find information about it but nobody knows what it is, could you find out the name of it?
Signature: Shawn Yoder

Giant Water Bug

Hi Shawn,
This is a Giant Water Bug in the genus
Lethocerus, and it is most likely one of five native species, though it has similar looking relatives in other parts of the world.  Alas, we haven’t the necessary skills to determine if this is a native species or one of its foreign relatives, however, we suspect it is native.  You can view photos of the natives on BugGuide. Giant Water Bugs are not beetles, as you have observed, and they are also called Toe-Biters since their bite is reported to be quite painful and Electric Light Bugs since they are attracted to lights at night.  They are the largest True Bugs in North America, though foreign relatives, especially those in Southeast Asia where they are eaten as delicacies, are significantly larger.  If your specimen was truly over four inches in length, it might well be a foreign import as North American individuals are allegedly only three inches in length.

Letter 8 – Giant Water Bug


Water Beetle
Location: Thunder Bay, ON Canada
October 23, 2011 9:00 am
Found this bug in my pond. When I accidentally scooped him out of the water on to his back. He easily flipped himself over and went straight back into the water. I’m assuming its some type of water beetle can you tell me any more about it. Do they bite?
Signature: Pond Beetle

Giant Water Bug

Dear Pond Beetle,
Giant Water Bugs are not beetles.  They are True Bugs.  They are commonly called Toe-Biters and they can deliver a painful bite if carelessly handled or accidentally encountered in the water.

Letter 9 – Giant Water Bug


Identification help
Location: Red Rock Canyon Nat. Conservation Area, Las Vegas
March 20, 2012 10:47 pm
I think this is a Giant Water Bug in the genus Abedus, but I’ve not been able to find images of Abedus or its relatives showing the paddle shape on the end of the front legs. Thus, I’m wondering if my ID is incorrect. This is about 2.5 cm long and was netted from a riparian pool
Signature: Bruce Lund

Giant Water Bug

Hi Bruce,
We agree that this is a Giant Water Bug in the genus
Abedus.  Most photos do not provide a good view of the raptorial front legs, however we did find an image on BugGuide that shows the well developed forelegs.  Though not as impressively large as the Eastern Toe-Biter, Western Giant Water Bugs in the genus Abedus are fascinating creatures.  The male carries the eggs on his backwhere they have been cemented by the female, providing some degree of paternal care, a relative rarity in the insect world.

Giant Water Bug

Thanks once again, Daniel.  I’ll look at Bugguide again – I missed the
image you found.
Bruce Lund


Letter 10 – Giant Water Bug


large (3” -4”?) water insect
Location: Madera Canyon, 20mi. south of Tucson, AZ
April 6, 2012 5:44 pm
What is this?
It was in a quiet pool at the edge of a mountain stream. We photographed it while still in the water.
Signature: GNB Arnold

Giant Water Bug

Dear GNB Arnold,
This is one of the Giant Water Bugs in the family Belostomatidae, and we believe it is a member of the genus
Abedus that is found in the western states.  The parenting behavior of this genus is quite interesting.  The female cements the eggs to the back of the male who carries them about until they hatch.  It is a rare instance of paternal parenting among insects.  See BugGuide for additional information on the genus Abedus.

Letter 11 – Giant Water Bug


Subject: Would like to be informed what this bug is ?
Location: Edmonton Alberta
June 12, 2014 11:36 am
I live in Edmonton Alberta and on a job site in the dirt we found this bug we are all very curious what it is ??
Signature: Thanks bug man !

Giant Water Bug
Giant Water Bug

While we cannot make out details, we are quite certain that this is a Giant Water Bug in the family Belostomatidae.

Letter 12 – Giant Water Bug


Subject: What is this!?!?
Location: Arizona
November 8, 2015 6:47 am
This odd creature was found, no clue what he/she is! The eyes tell you a story that is unknown.
Signature: Timothy

Giant Water Bug
Giant Water Bug

Dear Timothy,
This is a Giant Water Bug or Toe-Biter in the family Belostomatidae.  They are aquatic predators that can also fly from pond to pond, and they are sometimes found in swimming pools.

Letter 13 – Giant Water Bug


Subject: Swimming/Flying Bug
Location: Southwest Houston, TX
April 23, 2017 4:01 pm
I found this bug swimming in my pool the other day. I got it out and onto a pool mat. After sitting there for awhile it flew off. It was maybe a 1/2 inch long and had a line across it’s back that appeared to open and close almost like it was breathing.
Signature: TX Bug

Giant Water Bug

This is a Giant Water Bug in the genus Belostoma, and while it is nowhere near as large as the Toe-Biters in the genus Lethocerus, they are impressive nonetheless.  Handle with caution as Giant Water Bugs are capable of biting.

Letter 14 – Giant Water Bug


Subject:  Big bug
Geographic location of the bug:  Arizona
Date: 03/05/2019
Time: 03:53 PM EDT
Your letter to the bugman:  Found this floating dead in a pond, haven’t seen it b4
How you want your letter signed:  Anthony

Giant Water Bug

Dear Anthony,
This is a Giant Water Bug or Toe-Biter, and aquatic predator that is capable of flying from pond to pond in the event its habitat dries up.  We believe this is
Lethocerus medius, a species reported in Arizona, according to BugGuide.

Giant Water Bug


  • 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.

  • 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.

2 thoughts on “What Do Giant Water Bugs Eat: A Quick Guide for the Curious”

  1. Yup this one is edible also.
    Not only Lethocerus but also the genera listed above have histories of consumption. In fact I’ve read that “most aquatic insects are edible,” a statement I find intriguing and only slightly dangerous. These particular guys are eaten in Amazonia.

  2. Found one our my back seat of truck with my kids and the truck came to a screening stop Chinese exit and a or of screaming and the bugs was ruching out also not sure if it was trying to get us lol.


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