Water Bug vs Cockroach: How To Identify Both

Water bugs are often compared to cockroaches. Both can have a similar size, a similar shape, and even a similar color. Water bugs are different from cockroaches and telling the difference is important when it comes to proper pest control.

Certain species of water bugs resemble some cockroaches. The Giant water bug mostly resembles the American cockroach. Both have a long brown body with 6 legs. Water bugs live in the water while cockroaches are terrestrial crawlers.

Water bugs are often seen around the house, especially in the pool. It takes consistent effort to clear the pool of water bugs.

First, you need to ensure you have a water bug problem. You then need to skin the water and also use a pool vacuum cleaner to remove all water algae. You then need to shock the swimming pool to keep water bugs out.

Cockroaches are mostly eliminated by removing foods and by reducing humidity levels indoors. They don’t enter the pool as they mostly stay in the kitchen or outdoors where they feed on garbage.

Getting rid of these pests requires different techniques. But you need to properly identify each species first.

Which water bugs resemble cockroaches?

Water bugs are a common occurrence in streams, ponds, marshes, and rivers. These types of bugs can be scavengers or predators, depending on their species.

Scavenger water bugs feed on plant algae and can be seen in pools whenever algae start to grow in the water. These scavenger water bugs attract predatory water bugs which see them as food. Both types of water bugs can resemble cockroaches.

Giant water bugs

The Giant water bug is commonly misidentified as an Oriental or American cockroach. The physical resemblance is high, but you need to know how to distinguish these species.

These bugs are large, as their name implies. They grow to a maximum size of 4 – 4.5 inches.

Giant water bugs are a predatory species known to eat small fish and insects. These water bugs are mostly seen in freshwater and pools, just under the surface of the water.

Giant water bugs have distinct raptorial legs. These legs make them different from cockroaches as they use the raptorial legs to grab their prey.

One of the biggest differences between these bugs and cockroaches is the ability to bite. Giant water bugs can bite people.

Giant Water Bug

Water boatmen

Water boatmen are bugs that live in the water and that have brown or black striations on dorsal sides. These bugs resemble cockroaches in their size as they can grow up to 1.6 inches.

Water boatmen represent one of the most common bug species in pools. These water bugs only eat algae which is why they stop in certain pools.

They possess adapted forelegs which allow them to scoop algae for consumption easily.

Both the habitat and these adapted forelegs help you identify the species and differentiate it from other brown or black cockroaches.

These roaches cannot be eliminated from pools unless the water is clean and algae-free.

As forages, these bugs are also known to attract predatory water bugs. All Water boatmen can attract Backswimmers who see them as prey.

water boatman on water

Water scorpion

Water scorpions are brown insects that resemble Oriental cockroaches. However, Water scorpions aren’t at the bottom of the food chain eating leftovers and garbage. Water scorpions are predatory insects.

Based on agile raptorial forelegs, Water scorpions can eat a large number of insects and fish inside the water.

These brown insects grow up to 1.8 inches, which makes them similar in size to cockroaches. They even have a pear-shaped body that resembles roaches. It’s the raptorial forelegs and the aquatic environment that makes Water scorpions truly different than cockroaches.


Backswimmers get their name from swimming on their backs. These small insects are smaller than many roaches, only growing to maximum body size of 0.6 inches.

You can identify these insects when you see them floating upside down with their legs and abdomen up.

Backswimmers can bite and they are known predators of Water boatmen. This makes them a distinct species that has a different habitat and a different diet compared to cockroaches.

backswimmer on water

What do cockroaches look like?

Cockroaches share many of these physical traits of water bugs. They also grow up to a few inches. Cockroaches also come in gray, brown, and gray colors. Cockroaches also have 3 pairs of legs.

But cockroaches live in different areas, mainly next to animals and foods that include decaying food. They don’t enter the water as they drown quickly.

American cockroach

The American cockroach is one of the most popular roaches in North America. This brown oval-shaped insect grows to a maximum size of 1.6 inches, similarly to Water scorpions.

You can quickly tell the difference between these roaches and water bugs by their habitat. American cockroaches don’t enter the water, they live on dry land and inside homes.

The diet of these roaches is also very different. American cockroaches eat fermenting foods such as fruit, pet food, and even cardboard. These roaches are highly common around the kitchen.

Oriental cockroach

The Oriental cockroach has a dark brown color. It has 3 pairs of legs and it grows to a size of around 1 inch, similarly to Backswimmers.

Oriental cockroaches have a wider body compared to Backswimmers. They also have different habitats and different diets.

All Oriental cockroaches can enter homes as pests. It’s here they eat decaying food and all organic matter from the kitchen, bathroom, or garbage cans.

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German cockroach

The German cockroach has a brown color, similar to the color of the Giant Water bug. It has a small body as it only grows to 0.6 inches.

These roaches like humidity but they don’t live in water. They prefer the high indoor humidity specific to bathrooms.

Roaches of this genus are known to eat meats and sugar-rich foods as well as any leftovers they can find around homes and out in nature.

german cockroach

Major differences between water bugs and cockroaches

Both water bugs and cockroaches can be seen as home pests. They are known to invade homes in the summer even if some of these species can even overwinter indoors. They are different in many regards.


The habitat is the major difference between these bugs. Water bugs are tied to living in slow-moving water. They need algae, fish, or insects to survive.

Water bugs aren’t known for invading homes. Cockroaches live on dry land and they often make their way indoors. These bugs are known for having a major impact on sanitation and health.


Cockroaches are found at the bottom of the food chain. They eat all types of food including dead animals and decaying food.

Water bugs are more selective in their foods. They only eat algae, living fish, or living insects. While physically similar to cockroaches, water bugs have their diets or food preferences.

Biting capacity

Cockroaches don’t bite. They run away when seeing people. A good number of water bugs bite, on the other hand. Numerous cases of people being bitten in the pool are reported each year.

Most cases of water bug bites aren’t followed by an infection. But these bites are still painful.

Similarities between water bugs and cockroaches

Water bugs and cockroaches have a few good similarities. Most of these confuse as many don’t know the differences between these species.


Water bugs and cockroaches are brown, black, or gray. These are the most common colors of these bugs but they are often confused with cockroaches since both types of bugs can have similar sizing.


Water bugs can grow up to 4.5 inches while common cockroaches only grow up to 2 inches. However, many species have a similar size and 3 pairs of legs which causes some confusion.

One of the easiest methods to differentiate water bugs from cockroaches is by looking at their environment. Water bugs are rarely seen outside water and outside pools when invading homes.

Cockroaches can’t swim. While you might see cockroaches in your toilet in case of a bathroom invasion, it’s rarely the case these roaches are alive. They climb and fall into the toilet and eventually drown without a means of escape.


Water bugs are first identified by their habitat. They live in slow-moving waters rich in algae, fish, insects, or other water bugs which all serve as food.

Cockroaches are seen on dry land where they often invade homes to find food and to seek shelter. While both cockroaches and water bugs can be nocturnal and attracted to light, they move to different areas of the home.

Water bugs settle in dirty pools or pools with algae easily. Cockroaches take advantage of holes or openings around doors and windows to enter homes and nest in hot, humid, or food-rich areas such as bathrooms or kitchens.

Maintaining a clean pool is mandatory to keep water bugs out. A clean home without any water leaks and with sealed cracks and other entry points is required to keep cockroaches out.

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