Cockroaches are one of the most reviled insects on the planet. They’re known for scurrying around in the dark, scattering in the light, and making a mess of already messy things like garbage and clutter. Cockroaches are omnivores that eat everything from waste to plant matter. But, just what do cockroaches look like? There are over 4,000 species of cockroach worldwide, and each has its own distinct size and coloring. But, they all share the same generalized body type and features.
Here, we’ll learn more about what cockroaches look like, and why they look the way they do. We’ll go in depth on the cockroach life cycle—and how their appearance changes with age. Then, we’ll take a closer look at some of the insect species most commonly mistaken for cockroaches, and how you can tell them apart. Finally, we’ll go over the signs of a cockroach infestation, and what you should watch out for.
What Do Cockroaches Look Like?
Cockroach species vary widely, but most are between 1-2 inches long, and less than an inch wide. The smallest species (like the three-lined cockroach) grow to only a quarter of an inch long, while the largest (like the Central American giant cockroach) can grow up to four inches long.
Some species are long and thin, while others resemble a flattened egg in shape. If you’ve ever seen a cockroach in your home or foraging in a dumpster, then you probably have a pretty good idea of what they look like. Let’s take a closer look at their specific features throughout their life cycles.
All cockroaches start out as eggs inside of egg cases. Depending on the species, the mother cockroach may keep the egg case inside of her until the baby cockroaches hatch, or deposit the egg case in a safe place for incubation. Egg cases typically look like small, dried kidney beans—but they can range in color from almost black to nearly translucent tan.
Inside the egg case, baby cockroaches develop within their eggs for anywhere from a month to several months. When they’re ready to hatch, they break out of their eggs, then out of the egg case. The infant cockroaches have just entered their second life stage, and are now known as nymphs—baby cockroaches.
Nymphs are tiny and so lightly colored that they’re almost translucent. They’re commonly mistaken for albino cockroaches. But, in reality, there are no albino cockroaches, only young, pale cockroaches.
As the nymphs grow, their soft inner body grows larger, which means they have to shed their hardening exoskeleton periodically to make room. This is called molting, and every time the nymph molts, it looks a little more like an adult cockroach.
Nymphs have the same general body shape and parts as adult cockroaches, just in miniature, white form. They have six legs, a head, thorax, and abdomen. Though most cockroach species have wings; they don’t grow them until adulthood. The nymph stage can last anywhere from a few weeks to a few years—depending on the species.
Adult cockroaches look like, well—cockroaches. After the final molting, the one that takes them from nymph to adult, they molt no more. At this point, they have the hardened, darkened exoskeleton that they’ll have for the rest of their adult life.
Adult cockroaches look similar to beetles, but they’re actually more closely related to termites. They have long antennae (the length of their entire body) and fully developed legs that come equipped with spines along their length. They’ve also got something the nymphs don’t have; wings.
Many species of cockroach have only vestigial (un-usable) wings, or wings that are only capable of short glides, rather than true flight. Some have true wings, though these species are few. Often, males of the species have larger and more functional wings than females. But, no matter the size of the wing, they all have one distinctive feature; their head.
Cockroach heads are covered by a hard shield called a pronotum. When you look down at a cockroach, this is what you see, rather than the head. In fact, their heads are nearly invisible from above. In order to really see the head, you would have to look at the cockroach from the side or below.
Cockroaches look like specialized insects, but they’re actually one of the most generalized of all bugs. Their heads are no exception; the mouthparts are so simple that scientists think they may not have changed in millions of years. Unusually, their heads are attached to their bodies at a 90 degree angle. If human heads were set onto our bodies in the same way—our eyes and mouths would point straight up to the sky, all the time.
What Bugs Are Often Mistaken For Cockroaches?
Cockroaches look like many other species of insect, particularly as they’re growing and their looks change. In particular, they’re often mistaken for water bugs, or beetles. Given that some species of cockroach (like the Australian rhinoceros cockroach) have no wings, and ovoid bodies with heavily segmented abdomens—it’s no wonder people think they’re beetles, or vice versa.
There’s even one species of cockroach—the domino cockroach—that has evolved specifically to look like an aggressive species of beetle that lives in the same habitat. These cockroaches are black, with lady bug shaped bodies, and seven white spots arranged on their back.
Signs of a Cockroach Infestation
Of the approximately 4,500 species of cockroach, only about 30 (like the American cockroach) ever come into natural contact with humans. Of these 30 though, a few can be incredibly destructive and disgusting if they take up residence in your home or business. The easiest way to tell if you have cockroaches is to look for cockroach droppings or shed exoskeletons. You can also put out glue traps at the bases of walls, under furniture, or under sinks. If you find cockroaches on the traps, then you’ve got a problem.