Saw a big brown water bug crawling underneath your sink? You’ve heard of these pests but might not have cared about them before. Now you want to figure out exactly what you’ve found.

Water bug identification can be a little bit confusing. Not just because there are different types of water bugs. But because there’s conflicting information.

In this short guide, you’ll learn how to tell these insects apart, and what to do to stop them.

Let’s take a look!

Are Water Bugs and Cockroaches the Same?

Yes and no.

“Water bug” is indeed a term many people use to refer to cockroaches. But it usually doesn’t refer to all cockroaches, just the peridomestic roaches (the American, Oriental, and smokybrown roaches) that prefer to live outdoors.

These roaches don’t live in water, but in close proximity to it—in the moist trash dumps, wet sewers, and humid compost around our homes. When these harborages get disrupted or the weather gets too bad, the roaches there may go in search of better conditions, sometimes ending up inside our homes.

There’s another type of water bug however, which isn’t a cockroach—the giant water bug, and it’s not a threat inside your home. Let’s look at that outlier first then ID the cockroach/water bugs one by one.

The Giant Water Bug (Isn’t Interested in Your House)

Illustration of a giant Florida Waterbug ("Toe Biter Bug") in grass

The giant water bug (Lethocerus americanus) a member of the order Hemiptera, is altogether different from any cockroach you’ve ever seen. Also called the “toe biter” or “electric light bug,” it’s sometimes seen crawling on porch lights, but seldom makes its way inside.


  • Size: 2–4 inches in length
  • Color: Grayish dark brown, similar to a dead leaf
  • Range: Across North America, especially southern Canada and the U.S.
  • Habitat: Fresh water, including ponds, streams and the edges of lakes
  • Risks: A giant water bug has been known to bite humans when handled.

American Cockroaches (The American Water Bug)

American cockroach adult, nymph, and egg sac beside penny for scale
One of three different types of water bugs, the American cockroach, its nymph on the left, its egg sac on the right.

American cockroaches are the insects most commonly referred to as water bugs.

They’re large—in fact the largest pest cockroach in the United States. Both males and females are capable of flight, but are not good flyers. They live in dark, damp places but like other roaches below, don’t live in water. They’re scavengers with terrible eating habits, feeding on trash, waste and other decaying organic material.


  • Size: 1.5–2 inches in length.
  • Color: Reddish brown with yellow markings behind its head.
  • Range: Across the U.S., in areas both urban and rural.
  • Habitat: Outdoors in dark, warm, damp environments, such as sewers and drain pipes; indoors in kitchens and bathrooms, near food and water.
  • Risks: American cockroaches are known to carry dangerous bacteria and allergens that can contaminate your home. If left unchecked, they can infest in large numbers, cause damage, and put your family’s health at risk.

The American Water Bug Nymph

American cockroach nymphs measure 1/8 inch long when born, and throughout their maturation, look like miniature adults (minus wings). They take 600 days to reach adulthood.

Oriental Cockroaches

Oriental cockroach identification: adult, nymph and egg capsule beside penny for scale

The Oriental cockroach is found in cooler locations with lots of moisture. Unlike other pest roaches, it’s slow-moving, a poor climber, and doesn’t fly.

Its exoskeleton is dark brown to black in color, with a glossy sheen. It has a squatter shape than the American cockroach, and has significantly smaller wings (females’ are almost invisible).


  • Size: 1–1.5 inches
  • Color: Shiny dark brown or black
  • Range: Around the world, especially the northwest, midwest and southern U.S.
  • Habitat: Cool, humid environments, like basements, piping, laundry rooms and dumpsters.
  • Risks: An Oriental roach can lay 115 eggs per year, so the risk of infestation is high. They can survive on garbage and unsealed food, spreading widely in homes via pipes and cracks in walls. The bacteria they carry can cause stomach illnesses. They also produce a musty stench that’s difficult to eliminate.

The Oriental Water Bug Nymph

Like other roaches, Oriental cockroach nymphs look like smaller, albeit completely wingless versions of the adults. Oriental roach nymphs take about a year to reach adulthood.

Smokybrown Cockroaches

Smokybrown cockroach adult, nymph and egg beside a U.S. penny for scale

Smokybrown cockroaches are strong flyers that are attracted to lights. They sometimes follow lights into living spaces, but more frequently end up in garages, crawl spaces, and attics, where they need a humid environment to survive.

Smokybrowns have long shiny wings and bodies that are uniformly brown.


  • Size: 1.25–1.5 inches
  • Color: Uniform dark or mahogany brown
  • Range: Across the U.S., especially the Southeast
  • Habitat: Warm, humid areas, like attics, water meter boxes sewer access openings and roof shingles
  • Risks: Smokybrown roaches can spread if left alone, damaging photos and important documents as they feed and lay egg cases. Attics are especially problematic..

Smokybrown Cockroach Nymphs

Smokybrown nymphs are wingless and have distinctive markings—a pair of white stripes on the front half of their bodies and white-tipped antennae. Smokybrown cockroach nymphs take 320 days to reach adulthood.

Not to Be Confused with a Water Bug: The German Cockroach.

German cockroach nymph, adult, and egg, compared to a penny for size

Now, a German cockroach is not a water bug by any definition. But these roaches are such widespread household pests that some people lump them all together.

The German cockroach is an indoor species, unlike all of the other bugs on this list. It’s much tinier, capable of hiding in the loose seams of wooden furniture and the electronics inside appliances. They come inside by riding in bags, boxes and clothing.

German roaches multiply extremely quickly and, because they’re so tiny, they could establish a colony before you’ve even seen a roach. They’re considered by many pest control professionals to be the most difficult species to control.


  • Size: 0.5 inches
  • Color: Light brown, tan or golden with a pair of dark, vertical stripes on its back
  • Range: Across the U.S., in close proximity to people
  • Habitat: Warm, humid areas of homes, businesses and shared living complexes
  • Risks: High risk of infestation. German cockroaches can hide and breed in countless places, allowing them to multiply quickly and spread dangerous bacteria around your home. German roach skins and droppings can trigger allergies and asthma, too.

If you think that you’re dealing with these pests, jump over to our step-by-step guide to getting rid of German roaches.

German Cockroach Nymphs

Baby German cockroaches look like miniature versions of the adults but lack wings.

You’ll notice the pair of dark stripes running from head to rear cerci. A German roach nymph that’s just hatched or molted might appear gray or white. When it’s born, it’s only about the size of a grain of rice. It takes a mere 60 days to reach adulthood, increasing the risk of a cockroach infestation.


While roaches aren’t the only kind of water bug, they’re usually the ones that cause problems. They’re also (for most folks) not just any kind of roach, but one of several outdoor species. Each with unique risks and challenges.

Water bug identification is an important first step. You’ll want the next to be about action.

Head over to our water bug control guide to learn how to get rid of different types of water bugs permanently. There, we’ll show you how to create a roach-free home in four simple steps. To help you say—

Goodbye, water bugs!

Frequently Asked Questions

Are water bugs and roaches the same thing?

A true water bug—the giant water bug—isn’t a cockroach at all. However, most people who talk about water bugs are actually talking about one of several species of outdoor cockroaches (see above).

What’s the difference between a water bug and a roach?

Water bugs and roaches are different types of insects. The giant water bug is the largest “true bug” and a member of the order Hemiptera. It’s an aggressive, aquatic predator but not a household pest. Don’t handle one, though; you definitely don’t want a painful water bug bite.

A roach, on the other hand, is a potentially harmful pest in homes and businesses. It’s an insect of the order Blattodea. It inhabits damp, humid environments but doesn’t live in water.

Do water bugs eat roaches?

Giant water bugs, like Lethocerus americanus, hunt many kinds of small prey, from tadpoles and fish to crustaceans and snakes. They also eat other insects, though cockroaches aren’t a common staple of their diet because roaches live on dry land.

How big are water bugs?

Giant water bugs grow as long as 4 inches, with large front legs and a wide, oval-shaped body. The cockroaches typically called “water bugs” range from 1–2 inches in length.


  1. Gray, Betty. Giant Water Bug. Texas A&M: Beneficials in the Garden & Landscape. Retrieved from
  2. Choate, Paul M. (2019) Giant water bugs, electric light bugs. University of Florida Entomology. Retrieved from
  3. 2019 State of the Cockroach Control Market (2019) Zoecon/Central Life Sciences.
  4. Giant Water Bug. (2020) U.S. National Park Service. Retrieved from

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