Oriental Cockroaches

  • Written By Dan Edwards on August 9, 2018
    Last Updated: November 25, 2020

There are more than 3,000 species of cockroach in the world. Less than one percent of these are considered a nuisance to humans. One of these pest species is the Oriental cockroach.

This roach is a bit different from the other kinds we can find in our homes, such as the American and German cockroaches. Today, we will put the Oriental roach under the microscope and take a closer look at its appearance. We’ll also take a glimpse at its hiding places and, most importantly, how to get rid of them.

What Do Oriental Roaches Look Like?

The standard description of a cockroach is of a reddish-brown, oval-shaped bug with long antennae. The Oriental roach, however, is not quite the same. This species originated from regions around the Black and Caspian seas, likely coming to the U.S. via travelers and shipments.

Much like other species, the Oriental cockroach goes through three life stages—egg, nymph, and adult. Although eggs and nymphs aren’t that big of a threat yet, knowing what they look like is essential when identifying the nest.

Let’s see what the Oriental cockroach looks like in each life stage.


The Oriental cockroach eggs are kept within a capsule, called an ootheca. These egg casings are approximately 0.31 to 0.36 inches in length and can hold about 16 eggs at a time. Inside, the eggs line up vertically two by two, thereby creating more space.

The ootheca resembles a small kidney bean. The shell generally has a shiny, reddish-brown appearance.

The female roach will usually carry the ootheca at the end of her body for anywhere between 12 hours and five days. Once she feels ready, she deposits the casing in a safe place, where there is easy access to food and shelter.

The incubation period for this cockroach can be about 42 to 81 days. Females usually stay close to the eggs to protect them from possible danger. The eggs develop best at room temperature, anything colder will delay the process.


Nymphs are the immature cockroaches. Each species of cockroach will emerge from the eggs as nymphs, where they will go through a series of instars, or nymphal stages.

Once the nymphs emerge from the ootheca, they are on their own. The female doesn’t provide much maternal care, this may be because her lifespan is relatively short.

The nymph looks like a tiny cockroach. During the first few instars, the baby roach is smaller than the egg casing. It appears almost shapeless, lacking the adult segments.

Every time a molting takes place, the cockroach will lack pigmentation and so appear white. It usually takes about a day before the cuticles reach the normal brownish color.

After each molting, the nymph grows until it reaches the appropriate adult size. Every body section then becomes more apparent. This could take up to a year, where each nymph will go through seven to ten moltings.

During the nymphal stage, the immature roaches will develop all the characteristics of the adults. This includes reproductive organs and wings.


Many people tend to refer to the Oriental cockroaches as “water bugs” or “black beetle cockroaches”.  This is mainly since they often come out of drains and their bodies are shiny and dark.

The Oriental cockroach is smaller than the American roach, but larger than the German cockroach. Adult males usually reach about 1 inch in length and females tend to grow to approximately 1¼ inches. Although they are slightly smaller, their speed is much slower than that of their bigger cousins.

We often perceive this species as sluggish. Generally, cockroaches are quite strong climbers. They tend to sit upside down in cabinets or crawl on the ceiling. The Oriental roach, on the other hand, cannot climb smooth surfaces. These bugs are frequently found stuck in bathtubs and sinks for this reason.

Both genders of the Oriental species have wings, but they cannot fly. The wings on the male covers only half of his abdomen, while female wings are almost non-existent. These are mere stubs, resting on her back. The male may flap his wings to get away from danger quickly, but his wings are too small to fly.

The Oriental cockroach has a very dark brown, almost black color. Males are, however, a little lighter, with a yellowish color underneath their short wings. The exterior of the female resembles a leathery texture. Her tone is very dark and on the top of her back rests her two tiny wings.

This type of roach is especially unpleasant to have inside a home. They often emit a distinct roach smell, sort of musty and greasy. Did you know that cockroaches leave odor trails for their fellow roaches to follow? During large infestations, these smells tend to affect the whole area near the nest.


The Oriental cockroach is common throughout the U.S. Although it tends to stays outdoors in moist and damp places, it won’t hesitate to enter our homes. These roaches have very specific preferences, becoming distressed when conditions are less than ideal.

When the outside weather turns too hot, too windy, too dry or too wet, the Oriental cockroach will venture indoors.

Conversely, they can survive cooler temperatures. During the winters, these roaches will slow down their breeding cycle significantly.

Although Oriental cockroaches can survive the winter, they are usually seasonal. We generally don’t see many active adults until spring and summer, when temperatures peak.

Where Do Oriental Roaches Live?

Both adults and nymphs share the same habits and preferred living areas. They often find decaying organic matter, in which they love to hide. Outside, we can expect to see these roaches in dark, moist areas, for example: under porches, drains, and sewers.

They also enjoy hiding out in wells, water valve pits, and beneath shrubs. Yards seem to be a favorite, where they tend to stay around flowers and house foundations.

These roaches may also sneak into compost, or stone walls and crawl spaces. Their preferred meal is generally decaying matter, which is why we find them in trash chutes and garbage bins.

As these roaches are very sluggish and poor climbers, they will usually stay at ground level or below. Once inside the house, Oriental cockroaches favor a warm, moist basement. Water leaks generally attract large numbers of these insects.

Moisture is actually the main reason why the Oriental roaches venture indoors. They require a steady supply of water and high humidity level, to avoid dehydration.

This species sometimes enter our homes through ventilators, garbage chutes, or air ducts. They may even find their way in under the doors or through cracks and crevices.

Unfortunately, we can also bring them in with food packages or laundry. These lazy critters love to hide and sometimes we don’t notice them until it’s too late.


The Oriental cockroach will eat almost anything. Although it prefers to feast on decaying organic matter, it can also feed on the usual cockroach favorites. This can include anything from cereals or bread, to cardboard boxes and paper.

This species can also bite humans. Considering roaches will eat almost anything, during a mass infestation, food can become scarce. They quickly become desperate and will chew on anything that looks or smells edible. Most of the time, if a cockroach bites a person, it’s because there was food crumbs or residue on the person’s skin.

How to Get Rid of Oriental Roaches

The Oriental cockroach is a very unpleasant indoor guest. This is primarily because it feeds and harbors in moist, unsanitary places like mentioned above. Under its tiny wandering feet and underbelly lie a lot of bacteria and germs, ready to make you sick.

The roaches spread bacteria to our food supplies, kitchen surfaces, and utensils. The cockroach will wander over anything, contaminating whatever it comes in contact with. Not to mention the odorous secretions they leave behind, which have horrible effects on the flavor of nearby foods.

As a result of all the filthy material these cockroaches step in, they can cause various forms of intestinal conditions. This includes anything from diarrhea to food poisoning. Needless to say, therefore, getting rid of Oriental cockroaches is a must.

Fortunately these are simple cockroaches, thus there are several methods you can use to get them out of your home.

Eliminate Water Sources

Cockroaches need water, and as we have already established, Oriental cockroaches are no different. They can last up to one month without food, but will die within two weeks if there is no water.

If you live in a potential roach area, you should try to eliminate all water sources from your home. Even the tiniest leak behind your sink will contribute to their survival.

Make sure that you tighten all loose pipes and be sure to seal up the leaks. Dry out sinks and bathtubs after use. These roaches need less than an inch of water, therefore, even just the leftover puddles are enough.  

Check regularly under the refrigerator. This place is often dark and moist, perfect for these roaches. The same goes for your pet’s drinking bowl. Empty it every night before going to sleep. Cockroaches are nocturnal, so they come out during the night to feed.

Outdoors, be sure that you don’t overwater the flowerbeds and any other vegetation. Remove all potential water vessels, such as old tires, containers, and tubs. The roaches will gather around these things and likely invade your home once the weather cools.

Eliminate Hiding Spots

The next thing you want to do is make sure that there are no harbors for the pests. These critters love to hide in dark places, and will always shy away from open, well-lit areas.

Excess clutter around your home fits their requirements perfectly. The roaches will snuggle up inside just about anything, whether it’s a pile of laundry or a stack of old newspapers. This can also be the case outside where you’ve left a collection of old leaves or wood.

Juvenile Hormone Analogs (JHAs)

As the Oriental cockroaches love tiny cracks and crevices, it can be tricky to get to them with the insecticides. Juvenile hormone analogs (JHAs) is a relatively new method. JHAs work to disrupt the growth and reproductive developments of the immature roaches.

JHAs stops the development of the reproductive organs during the last few instars in juvenile nymphs. This method won’t necessarily kill them, but over time it will reduce the number of sexually mature adults. Thus working as a way of population control.

Traditional methods, such as pesticides, traps and gels, are also widely available. However, JHAs are safe to use around the home due to the low toxicity. Hopefully, in turn, they can help to effectively reduce the number of Oriental cockroaches snooping around our houses.