Water Bug vs Cockroach: What's the Difference?

Water bugs and cockroaches are frequently mistaken for one another due to some similarities in their features. However, there are distinct differences that set them apart. Below we’ll explain what these are so you’ll be better equipped to properly identify each one.

What Exactly is a Water Bug?

The term water bug is broadly used to refer to several kinds of bugs within the insect order Hemiptera (true bugs), with one of the most common being the giant water bug. Giant water bugs are also known as “toe biters” and “electric light bugs.” They’re often mistaken for beetles and cockroaches.

What are Cockroaches?

The four most common species in the United States are the American, brown-banded, German and Oriental cockroaches. Many species of cockroaches are incorrectly referred to as water bugs, particularly the American cockroach because it tends to gravitate to damp areas such as sewers.

Water Bug vs. Cockroach

So what makes a water bug a water bug? Here’s a checklist of its most distinguishing characteristics.



Water bugs, as you may have guessed, live in water the majority of the time. They’re most often found in ponds and lakes but since they’re such speedy swimmers, the chances of actually seeing them in the water are slim.


Water bugs are predators that hunt and kill insects, small fish and other small animals they’re able catch.

Painful bite 

Water bugs have a very painful bite. They often bite humans out of self-defense, earning them the nickname “toe biter.”

Flying bugs (commonly seen near lights).

 Water bugs fly from one body of water to another during mating season. While flying, they’re attracted to light and are often seen near parking lot lights and under porch lights—the reason for the “electric light bug” designation.

Very large

Giant water bugs are the largest true bug in the United States and Canada. While most are about two inches long and one inch wide, some species can grow up to four inches long.

Flat and oval, tan or brown. 

Water bugs have a somewhat flattened appearance with flat, oval-shaped bodies that are tan or brown.

Clawed front feet. 

They use their clawed front feet to capture larger prey.

Piercing mouth and pointed beak

 Water bugs’ piercing, sucking mouthparts and short, pointed beak on the underside of their heads are two distinguishing features.

Wings form an “X.” 

Wings overlap at the bottom of the abdomen and form an X-like pattern. While water bug nymphs look similar to adults, they’re much smaller and don’t have wings.

Short antennae 

Antennae of water bugs are shorter than their heads and are found under the eyes.

Here’s a checklist of the identifying attributes of cockroaches.


Frequently found in wood 

Cockroaches are often found in cardboard boxes or wood cabinets, as they have a preference for wood over other surface materials. Although they don’t live in water, they’re able to adapt to, and live in, different habitats.


Cockroaches have scavenger-like eating habits and will dine on any food that’s around rather than hunting and killing prey. They can be major pests in any building where food is handled, including homes, restaurants and hospitals.

Biting is extremely rare. 

Cockroaches don’t typically bite people but may do so under extreme conditions.  

Some have wings, but most can’t fly. 

Many cockroach species have fully developed wings, even though many aren’t able to fly. Others have short wings or no wings at all. As with water bugs, young cockroaches resemble adults but are smaller and wingless.

Not usually seen in light. 

Being nocturnal, cockroaches aren’t typically found near light of any sort. While difficult to spot, they’re usually seen scattering when a light is turned on.

Medium sized 

Cockroaches don’t get as large as water bugs. Most are between three-quarters of an inch to three inches long.

Flat and oval, tan or reddish-brown to black. 

Similar to water bugs, cockroaches also have a flattened appearance and oval-shaped bodies. Most are tan or reddish-brown to black in color.

Long antennae and “hairy” legs. 

Two of the most striking features of cockroaches are their long antennae (about the length of their flat bodies), and six legs that are covered with spines, giving them a hairy appearance.

Downward-facing head. 

The heads of cockroaches face downward so that when looking at one from above, its head is hidden from view.

Still Having Trouble Identifying a Water Bug vs. Cockroach?

It can still be difficult to tell a water bug apart from a cockroach even when equipped with the knowledge of their defining characteristics. If you have questions about whether you might be dealing with water bugs vs cockroaches, a Terminix® pest control specialist can help. Give us a call at 844-251-2164 or fill out a contact form online. Our experts are happy to assist you.