Water Bug

Last updated: October 17, 2022
Verified by: AZ Animals Staff
© Stephan Morris/Shutterstock.com

Some species of water bugs can deliver a painful bite when handled.


Water Bug Scientific Classification


Read our Complete Guide to Classification of Animals.

Water Bug Conservation Status

Water Bug Facts

insects, tadpoles, small fishes, insects, and other arthropods.
Main Prey
Name Of Young
Group Behavior
  • Solitary
Fun Fact
Some species of water bugs can deliver a painful bite when handled.
Most Distinctive Feature
Their first pair of legs is modified for catching prey
Distinctive Feature
Short antennae tucked into grooves behind their eyes
Aquatic freshwater habitats
Birds, fish, and frogs (especially bullfrogs and wasps.
  • Nocturnal
  • Solitary
Favorite Food
Common Name
Water bug

Water Bug Physical Characteristics

  • Brown
  • Dark Brown
Skin Type
1 year
2–3 inches

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Some species of water bugs can deliver a painful bite when handled. 


The name “water bug” refers to members of an infraorder of insects known as Nepomorpha. This group of insects consists of more than 2000 species of true bugs found worldwide except in the polar regions. Most species live in freshwater habitats. They are prolific predators that feed on other insects. Larger species may also prey on fishes and amphibians in the water. 

Water Bug Species, Types, and Scientific Name

Insects in the infraorder Nepomorpha are commonly referred to as water bugs. There are more than 2,000 species of insects in this group. They’re commonly called “true water bugs,” distinguishing them from other insects with the same nickname, such as the oriental cockroach. This group sometimes goes by the name Cryptocerata which means “the hidden-horned ones.” This refers to their antennae which are reduced and weak. Another common nickname for this group of insects is “toe biter.” This refers to their tendency to deliver a painful (but nontoxic) bite on the toes of unsuspecting human feet.

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Toe biters belong to the order Hemiptera. This is an order of insects commonly called true bugs. There are more than 80,000 species of trug bugs. Some of the most popular members of this group include aphids, leafhoppers, bed bugs, assassin bugs, and shield bugs. Most true bugs have sucking and piercing mouthparts. 

True water bugs are found in aquatic habitats worldwide except in the polar regions. They are grouped into seven superfamilies as highlighted below: 

  1. Nepoidea – Giant water bugs
  2. Corixoidea – Water boatmen
  3. Ochteroidea – Toad bugs and velvety shore bugs
  4. Aphelocheiroidea
  5. Naucoroidea – Creeping water bugs
  6. Notonectoidea – Backswimmers
  7. Pleoidea – Pygmy backswimmers

Appearance: How To Identify Water Bugs 

Except for a few species, most water bugs’ first pair of legs are modified for grabbing onto prey.

©iStock.com/Eric Kukulowicz

Waterbugs have flattened, elongated bodies, and they have flattened legs. They typically have two large compound eyes. However, they do not have ocelli (a type of simple eye), which is a common feature of many other insects in the suborder Heteroptera where they belong. 

Water bugs have short antennae that they can tuck into grooves behind their eyes. Although they’re aquatic, most adults cannot breathe underwater. Instead, they possess a retractable breathing tube that can extend to the water surface for air. 

Except for a few species, most water bugs’ first pair of legs are modified for grabbing onto prey. Like other true bugs, all insects in this group have sucking and piercing mouthparts. They catch prey in their forelimbs and inject them with powerful saliva that immobilizes them. 

Given the variety of species, insects in this family vary in size considerably. The giant water bug, the biggest species in the group, measures up to 2–4 inches in length. Water scorpion, another large-sized species in the group, may measure between 0.6 and 1.8 inches in length. Members of the family Naucoridae are significantly smaller, usually about 0.2–0.8 inches long. They are typically tan to dark brown. In most species, a wing pad is visible from their dorsal view. However, most species are flightless.

Habitat: Where To Find Water Bugs

Toe biters occur worldwide except in the polar regions, where they cannot thrive due to extremely cold temperatures. Most species in this infraorder are aquatic. They typically live in freshwater habitats. However, a few members, such as species in the superfamily Ochteroidea, only live along the water’s edge and not in the water itself. Despite being aquatic, most adults in this group cannot breathe underwater. They tend to use breathing tubes that can extend to the surface of the water and retract when not in use. 

Diet: What Do Water Bugs Eat?

Many of the insects in the Nepomorpha group are predators of other invertebrates. They mostly prey on other insects. However, larger ones, such as the giant water bug and water scorpion, can prey on small fish and amphibians. Many species are omnivorous, while a few of them feed on plants

As with all the true bugs, their mouthpart forms a rostrum which they use to pierce their food source and suck fluids from it. Some groups, like the Corixidae, can chew on their food before sucking the pulp. In some species, the rostrum is a stinging mouthpart that they can use to deliver a painful sting.

What Eats Water Bugs?

Water bugs have several predators. This includes birds, fish, and frogs (especially bullfrogs and wasps. Some species, especially toe biters, are a delicacy in south and southeast Asia. Water bugs have various defensive mechanisms against predators. For example, some species have stinging mouthparts and can deliver a painful bite when disturbed. Some species also emit a bad odor to repel predators. The flat, leaf-like appearance also serves as excellent camouflage. 

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Abdulmumin is a pharmacist and a top-rated content writer who can pretty much write on anything that can be researched on the internet. However, he particularly enjoys writing about animals, nature, and health. He loves animals, especially horses, and would love to have one someday.

Water Bug FAQs (Frequently Asked Questions) 

Are water bugs and roaches the same thing?

Although water bugs look like cockroaches, they’re not members of the same family. True water bugs are aquatic insects that live in or near water. Cockroaches are household pests and can survive without water. A major distinguishing feature between both insects is the lack of long antennae in the water bugs. Also, most species of water bugs have stinging mouthparts which they can use to defend themselves if threatened.


Are water bugs dangerous?

Most species of water bugs are not dangerous to man. However, a few species such as the giant water bug and the water scorpion have a proboscis which can deliver a painful bite similar to a bee sting. While the sting is painful, it is not very harmful to humans.


How do you identify  water bugs?

Water bugs have a long flattened body. They look similar to cockroaches but are usually a darker brown color. Also, unlike the cockroach, they do not have a long antenna and are mostly flightless. They’re found inside the water or near water bodies.

Thank you for reading! Have some feedback for us? Contact the AZ Animals editorial team.

  1. Wikipedia, Available here: https://en.wikipedia.org/wiki/Nepomorpha
  2. National Park Service / Sonya Daw, Available here: https://www.nps.gov/articles/giant-water-bug.htm

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