What is a Water Bug?

N. Madison
N. Madison

A water bug is a type of aquatic insect. Often people call a common house pest a water bug, but that bug is actually a large type of cockroach. Bugs in this category can belong to several different families, including the Notonectidae, Nepidae and Belostomatidae families. Water bugs are scientifically classified as belonging to the Hemiptera order. Boatmen (Corixade), water scorpions (Nepidae) and backswimmers (Notonectidae) are some of the most well-known waterbugs. Sometimes, however, the name water bug is used to refer to giant water bugs (Belostomatidae) to the exclusion of these other types of bugs.

A pond with water bugs.
A pond with water bugs.

Giant water bugs outdistance all the other aquatic bugs, coming in at more than 4.5 inches (11 cm) in length. These bugs are strong fliers and have mouth parts capable of piercing and sucking. A bite from one of these bugs can be serious, as they inject enzymes that break up proteins in their victims' bodies. Besides piercing mouths, these bugs have pointed beaks on the bottom portion of their heads; they also have wings that form an x-like pattern, overlapping the back portion of their abdomens. They eat fish, birds and various water animals.

An American cockroach, which is sometimes called a palmetto bug or a water bug.
An American cockroach, which is sometimes called a palmetto bug or a water bug.

Water boatmen are much smaller than the giant water bug, measuring about 1/2 inch (1.27 cm) long. They have long, hairy legs that are similar to boat oars on the back portions of their bodies and wide, rounded heads fitted with big eyes and rather short antennas. They have flattened bodies that are more long than wide. Their coloring is typically dull and mottled, and they are often confused with backswimmers because they are shaped similarly. This type of water bug swims upside down and has wings that are a lighter shade than its legs; they eat plant material, such as algae.

Water scorpions are a bit larger, coming in at about 1 to 2 inches (2.5 to 5 cm) long. These water bugs resemble land-based scorpions and have tails that look like whips. Surprisingly, these tails are actually breathing tubes. They have forelegs that resemble pincers, which they use to grab their prey, and they are meat eaters, consuming various pond animals. They do deliver a rather painful bite, but it is not as dangerous as a bite from a land scorpion.

Backswimmers are predators that swim upside down and have long hind legs that they use as oars. Their bodies are shaped like boats, and their abdomens are shaped like broad keels. Their underparts are lighter than their upper bodies, perhaps to help in camouflaging them when they swim. They can deliver painful bites, and they typically eat bloodworms and larvae. This type of water bug also carries an air bubble for breathing when underwater.

A bite from a giant water bug can be both painful and serious.
A bite from a giant water bug can be both painful and serious.
N. Madison
N. Madison

Nicole’s thirst for knowledge inspired her to become a wiseGEEK writer, and she focuses primarily on topics such as homeschooling, parenting, health, science, and business. When not writing or spending time with her four children, Nicole enjoys reading, camping, and going to the beach.

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Discussion Comments


I love reading about nature topics, particularly when bugs are featured! They are endlessly fascinating to me, and I'd love to have some as pets one day.

Some species of water bugs leave the job of baby care to the male. He carries the eggs on his back, which is kind of neat I think.


@Valencia - It's a pity that this fear is spoiling your chance to relax with friends. I remember my father telling me that in general waterbugs prefer still water. So you are going to see less of them in rivers or any free flowing water.

As many types of waterbug can't breathe underwater you should be able to see them quite easily on the water's surface.


I've had a phobia about swimming outdoors since I saw pictures of water bugs in science class at grade school!

When I go camping with friends or family I can't join in any water fun, and I know I need to get this into perspective.

Are there any places in particular where waterbugs hang out? Maybe some places are more popular with them?

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