Spotting any insect in your home can be unsettling—but when it’s the kind that might bite, things feel a bit more serious. While many bugs can make their way inside, it’s not always easy to know which ones are harmless and which are worth worrying about. Take water bugs, for example. Do they bite, or are they simply unpleasant to look at?
The answer isn’t entirely straightforward. The term “water bug” is often casually used to describe all sorts of critters—including cockroaches—because it sounds a little less alarming. But true water bugs are their own thing, and no, cockroaches don’t qualify.
To clear up the confusion, we spoke with four insect experts about what water bugs really are and whether they bite. Just in case you ever come across one in the wrong place (like your home), we also got two dermatologists to weigh in on what to do if you’re bitten.
What are water bugs?
True water bugs belong to a group of aquatic insects known as Hemiptera. These bugs actually live in water and include species like water boatmen, water striders, water scorpions and pond skaters.
“There are at least six families of aquatic bugs,” says entomologist Dr Lynn Kimsey. One standout is the giant water bug—an insect that’s hard to ignore. “Capable of reaching 10 centimetres in length, giant water bugs are one of several species that live in water,” says associate certified entomologist Cody James Pace. “They have a flat, oval-shaped body that helps them glide just beneath the surface.”
That said, many people use “water bug” to refer to cockroaches—especially large ones seen in damp areas. It’s not an accurate label, says urban entomologist Dan Suiter, but it’s a common one.
Do water bugs bite?
It depends on what kind of bug you’re dealing with. If it’s a giant water bug, then yes—it can bite, and quite painfully. “Water bugs can unleash a painful bite on their preferred prey—other insects, fish, reptiles, amphibians and other creatures in their aquatic habitats,” says Pace. If they feel threatened, they may also bite humans.
After capturing their prey, giant water bugs inject a toxic digestive enzyme to kill and break down their food. This same mechanism can cause pain and irritation if a person gets bitten.
Some water bugs from the Belostomatidae family—commonly known as toe biters—may also bite if disturbed, says Dr Kimsey. Swimming in a pond where they live, for example, could result in a surprise nip.
If your so-called “water bug” is actually a cockroach, you’re probably in the clear. “Cockroaches have chewing mouthparts, so they are technically capable of biting,” says pest management expert Matt Frye. “But they’re not aggressive towards people and are unlikely to cause harm.”
Are water bug bites harmful?
If you do get bitten by a giant water bug, it can be a very unpleasant experience. “The most significant risk is the bite itself,” says Pace. These insects use a needle-like mouthpart called a rostrum to pierce the skin and inject saliva. In humans, this can trigger intense, burning pain.
Common symptoms of a bite include:
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Redness at the site
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Localised swelling (which can spread)
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Tingling or numbness
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Rare allergic reactions, such as hives or difficulty breathing
“The pain usually peaks quickly and subsides within a few hours,” says Pace. “The bite typically heals without lasting damage, though the initial discomfort can be severe.”
How to treat water bug bites
If you’re bitten, rinse the area gently with mild soap and water, says dermatologist Dr Gary Goldenberg. “Applying an ice pack can help reduce swelling,” he adds. For pain, consider a non-steroidal anti-inflammatory such as ibuprofen.
“Try not to scratch or pick at the area,” says dermatologist Dr Ife J Rodney. “The pain usually fades after a few hours.”
If you notice excessive redness, swelling or any yellow discharge from the wound, those could be signs of infection. In that case, Dr Rodney recommends seeing a dermatologist as soon as possible.
How to get rid of water bugs
Water bugs often feed on mosquito larvae and other small pests, so they’re not entirely unwelcome in nature. But if they’ve made their way inside your home, it’s fair to want them out.
If you spot one or two, try to guide them back outside without touching them. “Avoid handling them directly,” says Pace. “If they’re in an unwanted area, gently relocate them without contact.” That could mean nudging them out with a broom or using a glass-and-paper method to catch and release them outdoors.
How to prevent water bugs
The best way to keep water bugs away is to remove what attracts them in the first place. “Make sure all food is properly stored, crumbs are cleaned up and excess water or damp areas are dried out,” says Pace. Keeping things tidy and dry reduces the chances of attracting them inside.
FAQ
Is a water bug the same thing as a cockroach?
Not quite. While they’re often confused, they’re not the same species. “Some cockroaches are commonly misidentified as water bugs,” Pace says. “But true water bugs are generally larger—around five centimetres or more—and prefer to live in water.”
How do water bugs get in your home?
They often sneak in through small gaps, such as under doors or cracks in walls. Frye recommends checking your home for any openings and sealing them up to keep water bugs out.
When should you call a pest management service for water bugs?
If you’re only seeing one or two, escorting them out and storing food properly might be enough. But if water bugs keep showing up or you suspect an infestation, it’s best to call a professional. “In cases of heavy infestations, I recommend contacting a licensed pest control expert,” says Suiter.
Bottom line
Water bugs aren’t aggressive, but that doesn’t mean you want them hanging around. If a few have found their way in, it’s usually safe to remove them gently. If it becomes a pattern, though, bring in the experts to take care of the problem before it gets out of hand.
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