Cockroach vs Water Bug: 5 Key Differences Explained

Water Bug vs Cockroach

Written by Krishna Maxwell

Updated: October 29, 2023

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Both cockroaches and water bugs are extremely common pests in the United States. They infest the same areas in the home, too, such as the basement, bathroom, kitchen, or laundry room. Which begs the question: are water bugs roaches?

Especially since you might have heard of a cockroach being referred to as a water bug. If you think that implies a water bug is a type of cockroach, you’d be right. The term “water bug” is broad and can apply to several different insects that live in freshwater or on the water’s surface. The amphibious cockroach is just one of 1500 species of water bugs, whereas cockroaches are land-dwelling. But when comparing the water bug vs cockroach, in what ways do they stand apart?

While dealing with them as pests, it is useful to tell the difference between the two to better handle them. Even without an infestation, it is helpful so you can be prepared if you ever encounter them. True water bugs are aquatic so are much less likely to be a problem in the home. Cockroaches can spread human diseases and trigger allergy and asthma symptoms so it is important to keep these pest out of your home.

We’ll go over all the differences between the water bug vs cockroach below so you can know what you are dealing with when you see it!

Comparing Cockroach vs Water Bug

CockroachWater Bug
Size.075-3 inches long2-4 inches long
ColorRed, brown, tan, blackBrown, tan, grey (Oriental is darker)
BodyFlat, oval body, no wings, long antennae, spine-covered legs, downward-facing headFlat, oval body, wings, short antennae, piercing mouth, pointed beak, clawed front feet
HabitatWarm, dark indoorsMoist, dark freshwater ponds, lakes; near lights
TaxonomyOrder Blattodea, different families, genera, and speciesBlatta orientalis or true waterbug (true bug order Hemiptera, infraorder Nepomorpha)
Group behaviorGroupSolitary except during the mating season
DietScavengerPredatory,  scavenger (algae, garbage)
TerminologyLand-dwelling cockroachAquatic, Oriental cockroach

5 Key Differences Between Cockroach and Water Bug

Cockroach vs Water Bug: Size

When comparing a water bug vs cockroach in size, the water bug always dominates the cockroach in size, measuring anywhere from 1 to 3.25 inches longer than any cockroach. Even if you don’t see them side-by-side, you can still have a good idea of which is which.

Cockroach vs Water Bug: Body

Cockroach vs waterbug. How do these insects differ from each other, in terms of appearance and physical features?

When discussing physical features, it’s important to keep in mind that we are simply distinguishing the Oriental cockroach, also called a water bug or black beetle, from land-dwelling cockroaches. The American, Smokybrown, German and Oriental cockroaches are all called “water bugs,” but the only aquatic species is the Oriental. Cockroaches all have flat, oval bodies with antennae. The land-dwelling roaches have long antennae, spine-covered legs that look hairy, downward-facing heads, and no wings. Water bugs, or Oriental cockroaches, have short antennae, wings, clawed front feet, a pointed, short beak, and piercing mouth.

Cockroach vs Water Bug: Habitat

When comparing the habitat of the water bug vs roach, the land-dwelling cockroach is adaptable, although it prefers warm, dark enclosed spaces, and will move indoors to escape the cold of winter. The water bug, on the other hand, prefers moist and dark areas near freshwater ponds and lakes. It is also seen flying near lights during mating season. Cockroaches do not have any wings (although some species can glide) and they shy away from any light. This is why cockroaches run away when you turn the light on in a previously dark room.

Cockroach vs Water Bug: Predators

Cockroach vs waterbug. Who’s more likely to get eaten by what? It’s all a matter of location in this case since different environments present different predator threats. Cockroaches are eaten by small mammals, insects, and arachnids. Water bugs are hunted by aquatic birds, fish and wasps. Both types of bug can become the prey of frogs and other amphibians. And, of course, they can both be terminated by the pest control efforts of human beings.

Cockroach vs Water Bug: Group Behavior

Cockroaches enjoy being surrounded by each other as often as possible. Water bugs are fairly solitary except for mating season. If you encounter either one, a little more investigating will tell you whether it is a solitary insect or there is a group of them. If it is alone, it is likely a water bug. If you find a group of them, they are cockroaches.

Cockroach vs Water Bug: Diet

The last section in our quest to respond to the question “are water bugs roaches?”, leads us to explore both arthropods’ dietary habits.

Both of these roaches can be scavengers. The difference between the water bug vs roach is the predominant diet. Cockroaches are scavengers and will feed on food, garbage, and rotting things. Water bugs are predatory and will hunt smaller creatures However, they’ll also feed on algae and garbage whenever possible.

If you live in an area where cockroaches or water bugs are common, it is important not to leave any food out or you might end up sharing your home with these unwanted guests.

How Many Types of Cockroaches Are There?

Types of Cockroach - Madagascar Hissing Cockroach

The Madagascar hissing cockroach is among the largest in the world.

©Keith Muzzioli/

While we’re on the subject of cockroaches (and water bugs), did it make you wonder how many types of roaches there are in the U.S. or worldwide? Believe it or not, there are over 4,500 different types of cockroaches on the planet! Maybe it’s not that surprising, given the jokes surrounding how cockroaches would likely survive a nuclear holocaust or any other type of catastrophe just fine.

In the United States, there are 69 species. Types that seem to be spoken of the most include American cockroaches, German cockroaches, brown-banded cockroaches, smoky brown cockroaches, and Oriental cockroaches (often referred to as waterbugs). Other American varieties are the Pennsylvania wood cockroach, three-lined cockroach, field cockroach, and Florida woods cockroach.

If cockroaches give you the heebie-jeebies, consider the top 5 largest cockroaches in the world:

  • Megaloblatta Longipennis – largest in the world at 3.5 inches long, 1.5 inches wide, and an 8-inch wingspan
  • Giant Burrowing Cockroach – 3.1 inches long, weight of 1.5 ounces
  • Blaberus giganteus
  • Madagascar Hissing Cockroach
  • Death’s Head Cockroach

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About the Author

Krishna is a lifelong animal owner and advocate. She owns and operates a small farm in upstate New York which she shares with three dogs, four donkeys, one mule, and a cat. She holds a Bachelors in Agricultural Technology and has extensive experience in animal health and welfare. When not working with her own animals and tending her farm, Krishna is helping other animal owners with behavior or management issues and teaching neighboring farmers about Regenerative Agriculture practices.

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