How to Get Rid of Water Bugs in Your House

Seeing a dark bug near a drain, bathroom, basement, garage, or crawl space? Many people call these “water bugs,” but indoor water bugs are often Oriental cockroaches — moisture-loving roaches that hide in damp, dark areas. To get rid of them, start by identifying the pest, fixing moisture problems, sealing entry points, removing food and clutter, and using targeted bait or professional treatment when activity continues.

Are water bugs actually cockroaches?

The term “water bug” may be used to describe a cockroach from the order Blattodea, the same insect order as the German cockroach and the American cockroach. When people use the term “water bug” for this insect, they are not talking about the freshwater swimmer that hunts tadpoles, but about “Blatta orientalis,” a cockroach common in various parts of the Western and Southern U.S.

It is easy to get confused with the term “water bug,” as true water bugs, known as giant water bugs, can grow up to four inches long, swim underwater, and even fly. While male “Oriental cockroach” water bugs have wings, they are flightless. Female “Oriental cockroaches” do not have wings at all. They do enjoy hanging out in very wet areas of the house, however. Strategies for pest control for these cockroaches bear a great resemblance to those for German and American cockroaches and include food grade diatomaceous earth, boric acid, and gel baits.

Strategies for dealing with the more aggressive giant water bugs include exercising caution around standing water, as these dangerous critters are even known to play dead before injecting their venom into humans. People should also be aware that they may encounter the larger, more aggressive variety of water bugs, the “giant water bug,” at night, as it is so attracted to electric lights that it has been known as the “electric-light bug.” Although it may be less common in household infestations, this flying giant water bug is a large, common insect in the United States and Canada. It is known as Lethocerus americanus.

What are Giant Water Bugs?

Giant water bugs come from the order Hemiptera, and the family Belostomatidae, like to live and swim in freshwater. Unlike cockroaches, which are land insects despite having a preference for humid air, giant water bugs frequently swim to catch their prey in the wild. Their diet consists of minnows and tadpoles, and even larger animals like turtles and snakes. Humans may encounter them on rural property if they have ponds or other areas of standing water. They should be wary, as these giant bugs are known to bite and inject venom.

What Causes Water Bugs in Your House?

Although giant water bugs are more likely to be found outdoors than indoors, their preference for very wet environments, leaky pipes, wet sinks, or areas of standing water can bring “Oriental cockroach” water bugs indoors. Like with standard cockroaches, keeping a less humid, cleaner environment can help avoid a water bug infestation. Specific water-related maintenance issues come into play more. For example, you might have standing water in a vacation home if you didn’t realize there had been a flood event. Or you might have a leaky pipe that hasn’t been checked in a while. Water bugs can enter a house through the pipes, sewer system, or gaps in walls, closing and sealing gaps is essential to preventing future issues as you manage an infestation.

What actually helps get rid of water bugs?

For indoor “water bugs,” focus on the same steps used for moisture-loving cockroaches:

• Fix leaks and reduce humidity.
• Clean drains, garbage areas, and food residue.
• Seal gaps around pipes, doors, vents, foundations, and utility openings.
• Remove clutter, cardboard, leaf litter, mulch buildup, and damp hiding places.
• Use cockroach baits or professional treatment when activity continues.

UC IPM specifically says baits provide better control than sprays when insecticides are used, and that good sanitation and exclusion are important for effective cockroach control.

Killing the bug you see does not always solve the problem. If the moisture, food, and entry points remain, more may keep showing up. Long-term control depends on reducing damp areas, sealing access points, cleaning food sources, and treating the hiding areas where roaches live.

When Should You Seek Help?

Sealing locations of water bug entry is effective if entry points are known, but many homeowners require assistance both to locate and to effectuate the sealing of walls in residence. The larger the infestation, the higher the likelihood that getting rid of it and preventing it in the future will not be a do-it-yourself job.

However, by frequently vacuuming, even in hard-to-reach spaces like under sofas or beds, and by emptying garbage regularly and cleaning up crumbs, homeowners can reduce the likelihood of a bad water bug infestation. They can limit the labor by only eating in certain designated areas of the house. Finally, they can ensure that leaks are fixed so that there isn’t an overly damp environment for the moisture-loving bugs to thrive in.