Many kinds of bugs can wind up in your home. But when you discover one that looks like it came in on purpose, you may begin to wonder if you have a cockroach problem.
In this guide, you’ll learn how to figure that out, starting with an easy question: how many legs do cockroaches have? Then, to narrow things down more, you’ll see a few other bugs that look like cockroaches so you can compare them.
Finally, you’ll see what several kinds of roaches look like, and with some helpful links, learn how to get rid of them (along with all their friends).
Let’s get to it!
Roach Legs: What They Look Like and What They Do
Like all insects, cockroaches have six legs. That alone doesn’t tell you exactly what your bug is, but at least you know it’s not a spider! (Those have eight legs. They’re arachnids, not insects.)
The Science of Cockroach Legs (Skip this section if you just need to identify the bugs)
Roach legs are slender, spiny and jointed. They come in three pairs, each of which is attached to a segment of the roach’s thorax—the “torso” part of its body.
The three pairs of legs serve different purposes and, thus, have different names.
- Right behind the head are the prothoracic legs, which the cockroach uses to slow itself down. They’re the shortest.
- In the middle are the mesothoracic legs, which help the insect adjust its speed, speeding up or slowing down as needed.
- At the rear are the metathoracic legs, the roach’s strong hind legs that propel it forward at speeds of up to 50 body lengths per second!
As a cockroach walks, it moves its middle leg on one side with the front and back legs on the opposite side. By alternating steps in this way, it gains incredible mobility on even the most difficult terrain.
Fun fact: When a roach is climbing upside-down on the ceiling, it takes slower, longer strides to better maintain contact and avoid falling off. This takes a lot of energy and care, so a roach runs much more slowly on the ceiling.
Other Important Cockroach Characteristics
In addition to its legs, you can begin to ID a cockroach by its color. Most are brown, tan, reddish-brown or black.
Roaches also have two long antennae, flat bodies, a small head, and wings (though in some species and sexes you can barely see them). If you were to examine a cockroach closely, you’d also find a pair of small tendril-like filaments called cerci at its base. If you were to discover a female cockroach carrying an egg case, you’d see the egg case protruding from behind, sometimes looking very much like part of the roach’s body.
Size is a less reliable characteristic since roach sizes vary widely. The very small German cockroach grows to only about 0.5 inches long. While the much larger American cockroach grows up to 2 inches in length.
Why You Might Not Always See Six Legs on a Cockroach
At first glance, you might see only four legs on the bug you’ve spotted, but that doesn’t mean you’re in the clear. Sometimes, a roach’s front legs are small enough to be hidden beneath its body, making it look like the insect has four legs.
Additionally, not every cockroach has six legs. A roach can live on after losing a leg or two as it scavenges and explores new environments. You might spot one with five or even four legs, hobbling along but refusing to leave you alone nonetheless.
One incredible part of the cockroach’s genome even allows these insects to regenerate lost legs! After enough time, that five-legged cockroach could return to its true six-legged form.
With the basics out of the way, we’re going to start narrowing down your suspect by eliminating some of the bugs that look like cockroaches.
How Cockroaches Are Different From Beetles
Most beetles have spiny legs, just like cockroaches. But beetles’ legs tend to be shorter than cockroach legs. On a ground beetle, an occasional household pest, you’ll notice that its mouth has pincers. You won’t find these on a cockroach.
You can also look at the wings (if it has any). Flying roaches have a single pair of long, thin wings. Beetles usually have two pairs of wings, one of which is thick and protective.
If the bug you saw was flying around your house and fluttered away as you tried to swat it, it probably wasn’t a cockroach.
Most roaches don’t like to fly. Even among the ones that can, they’re rarely very good at it. Roaches mostly use their wings to glide or “hop” to higher elevations. They like to keep their feet on the ground, where they’re fast runners.
How to Tell a Cockroach from a Cricket
With its huge hind legs, it’s hard to mistake a cricket for anything else. A roach’s six legs all look about the same, though they’re slightly different in length. But a cricket’s rear legs are much bigger than their other legs. They use them to make their signature chirping sound and to hop long distances.
Cockroaches are known for their flat, oval-shaped bodies. They can squeeze through tiny crevices because of that shape. Crickets aren’t as flat. They also tend to have bigger heads, while a roach’s head is tiny and almost completely covered by a cowl-like structure (it looks like armor behind its neck).
How to Correctly Identify a Cockroach
It’s going to be hard to tell with 100% certainty that you have a cockroach problem without seeing the bugs up close. For that, you’ll need a few sticky traps. These pest control products are inexpensive but extremely effective at catching, killing and, most importantly, revealing the bugs that have invaded your house.
One of the most popular sticky traps is the roach motel. To catch the bugs, place one roach motel close to the place where you saw the bug. Choose a spot that’s relatively hidden or out of the way—cockroaches don’t like to venture out in the open.
Depending on the size of the room, place 1–3 more traps, focusing on areas near appliances, large furniture or holes in the walls. If you can, put them behind or under the appliances or furniture, where insects would most likely hide.
The traps will attract any nearby roaches. By the next morning, you should have one (or more) trapped specimens to examine up close.
For more tips on identifying cockroaches and determining which species you’re dealing with, check out our guide to the types of roaches with pictures.
We started with a common first question: “how many legs do cockroaches have?” But you have to look a bit further than the legs to truly distinguish cockroaches from beetles, crickets and other insects that might’ve wandered into your home.
Don’t give the roaches a chance to get comfortable. Start getting rid of cockroaches today!
Frequently Asked Questions
A cockroach has six walking legs. Its legs attach in three pairs to its thorax. The front, prothoracic legs are its brakes. The middle, mesothoracic legs are for adjusting speed. And the rear, metathoracic legs are for pushing it forward.
The segment of a cockroach’s leg closest to the floor is called the tarsus, and it might be the most important part of the leg. Underneath each subsegment of the tarsus are tiny, adhesive organs that act like sticky pads, suctioning the roach’s feet to smooth or vertical surfaces. This allows it to scale vertical walls and even climb on ceilings.
Cockroaches can regrow legs. It has a stronger ability to regenerate limbs in its nymphal stage, but adult roaches can regrow lost legs, too.
Cockroaches can walk backwards but, like most animals, they’re not as fast or agile as when they’re moving forwards. Their smaller front legs simply aren’t designed to propel them as quickly as their large hind legs.
- Wilson, Tracy V. Cockroach Anatomy and Physiology. HowStuffWorks. Retrieved from https://animals.howstuffworks.com/insects/cockroach1.htm
- Li, Sheng, et al. (2018) The genomic and functional landscapes of developmental plasticity in the American cockroach. Nature. Retrieved from https://www.nature.com/articles/s41467–018–03281–1