Oriental Cockroaches – The Sewer Loving Pest

What Is an Oriental Cockroach?

The Oriental cockroach (Blatta orientalis) is a large peridomestic species of roach that lives mainly outside and thrives in sewers but will move into your house during the summer looking for dark and damp places to live.

Oriental cockroaches may have originated in Africa or south Russia, but they now exist in other countries such as the USA, Canada, and the UK.  This species is mainly active at night and is sometimes referred to as a “black beetle”, “water bug” or “Shad roach”.

Closeup black shiny oriental cockroach
Shiny Oriental cockroach that looks like a black beetle Image: Clemson University – USDA Cooperative Extension Slide Series, Bugwood.org

Are Oriental Cockroaches a Pest?

Yes, they definitely are a pest.

Just how bad are Oriental roaches?  They rank just behind German cockroaches as a public health pest, as they are among the dirtiest and most dangerous types of roach you can find in your home.   

Oriental roaches live in both clean and dirty environments, as do other peridomestic roaches.  And these dirty environments include scavenging in rotting garbage and living in sewers where they feed on human feces.  

What Do Oriental Cockroaches Eat?

As well as excrement and rotten garbage, they also eat decaying plant matter, dead animals, as well as food that we and our pets eat.  They like starchy foods but like other species of cockroaches, they’ll more or less eat anything.   

When they migrate into your home, they feed on your food, vomit, and defecate on it.  They also pick up harmful bacteria from the sewer on their bodies, legs, and feet that they leave behind on your countertops and anything else they crawl on, which can cause food poisoning and diarrhea. 

According to The WHO:

They are proven or suspected carriers of the organisms causing:

– diarrhea
– dysentery
– cholera
– leprosy
– plague
– typhoid fever
– viral diseases such as poliomyelitis. [1]

Blatta orientalis is also dangerous because their droppings and cast skins produce allergens that negatively affect air quality and can cause respiratory issues in some people, especially children.

What Do Oriental Cockroaches Look Like?

Picture of adult Oriental cockroach
Picture of adult Oriental cockroach. Credit: Clemson University – USDA Cooperative Extension Slide Series, Bugwood.org
  • These pests are sometimes called “black beetle cockroaches” because they have smooth, shiny, dark red-brown to black colored bodies.  
  • They have an oval shaped body with banded segments, two antennae and six spiny legs.
  • The males and females look different to each other – the males are only about 1 inch (2.5 cm) long and are slimmer than the female.  They have wings that only cover three-quarters of the body. 
  • The females are larger than the males and grow to about 1-1/4 inches (3.2 cm) long and have a broader body.  They have small wing pads but no wings. 
  • Neither the male nor the female can fly.
  • The Oriental roach moves more slowly than other roaches.
  • Unlike other peridomestic roaches, this one has difficulty climbing smooth vertical surfaces such as walls as it lacks a cushion-like pad between its claws for climbing.  

What Do Oriental Cockroach Nymphs Look Like?

  • First instar nymphs are a light brown color and around 6 mm long.
  • As they mature and molt their color gradually darkens to the same as the adults.   
  • The immature oriental roaches are similar in shape to the adults but they don’t have wings. 
  • The older roach nymphs are brown and people often have a hard time telling them apart from American cockroach nymphs.

Oriental Roach Life Cycle

The Oriental cockroach life cycle goes through three phases:

1. Egg

2. Nymph (baby)

3. Adulthood.

The adult female will produce about eight egg capsules over her adult life.  Each brown-black colored, purse-shaped egg capsule, or ootheca, is around 1-1.2 cm (10-12 mm) long and contains 16-18 eggs, with 8-9 on either side. 

This means the female can produce around 180 or more baby roaches. 

The egg capsule is formed within 24 hours of mating, and the female carries it around for about 30 hours before attaching it with saliva or dropping it into cracks and crevices near where they will have access to food.

The eggs will hatch in about 42 days at a temperature of 81.5°F (29.5°C) or around 81 days at 70°F (21°C). These immature roaches go through 7-10 molts before becoming adults, which can take between 24 and 130 weeks, depending on temperature.[2]

This species is more seasonal than other roaches so the adults and large nymphs become active in the spring when temperatures are around 59°F (15°C).  They are more noticeable from May to July which is when they look to get into homes.  As autumn approaches, the older generation dies off leaving the new adults to infest.

Additionally, Oriental cockroaches will infest your home when the weather becomes unsuitable for them, like becoming too hot or cold, too wet or dry, or simply when their population levels become so large they run out of space in your yard.  

How Long Do Oriental Cockroaches Live?

If they have access to water and food, adult male Oriental roaches live from 112-160 days and adult females for 35-190 days.  

Where Do Oriental Cockroaches Live?

Outside this pest prefers to live in damp places like landfills, sewers, and drains, in rotting garbage and around garbage cans, in mulch, loose wood, and under leaves in your yard as well as under porches.

During the summer months, Blatta orientalis looks for cooler and more humid environments which are when you’ll find roaches coming from outside into your home.

Foundations and walls often have gaps and cracks where they can enter.  They can also crawl under a door and through air ducts.  Common routes are through pipes and up through floor drains where large numbers of them usually enter from. 

Generally, this species of roach lives below or at ground level so it is usually found infesting:

  • basements
  • ground-floor apartments
  • crawl spaces
  • cellar
  • garage

Check under the refrigerator as this provides plenty of access to moisture, and around the washing machine, near leaky faucets and pipes, around the toilet, and under sinks. 

Although it’s rare, they can find their way to upper floors and hide in areas where there is moisture and humidity, so also check the plumbing areas in your kitchen and bathrooms.

In apartments, Orientals may follow trash chutes and water pipes to upper floors and will grow in number when they find suitable areas.

This cockroach species will always find the area that has the most moisture and the females can survive with just water and no food for about 32 days and 20 days for males.[3]

Signs of Oriental Cockroaches in Your House

Picture of Oriental roach adults, nymphs, and numerous egg capsules
Picture of Oriental roach adults, nymphs, and numerous egg capsules. Image: Liz Kasameyer, Johns Hopkins School of Public Health, Bugwood.org

Although they are usually found outside, there are typically three warning signs that you have an Oriental roach infestation in your home, and these are: 

1.  Seeing the insect in your home during the summer. A moist environment will allow them to survive and reproduce so focus your inspection on all of the other areas of high humidity mentioned above and look for other signs like fecal smears and droppings as well as dead roaches. 

2.  Finding egg capsules that will be dropped and hidden near sources of food. 

3. Odor from the chemicals this pest secretes is worse than the other home-infesting roaches.  The unpleasant, musty smell will become more noticeable and smelly as the infestation grows. 

Getting Rid of Oriental Cockroaches

Controlling an Oriental cockroach population is the same as controlling the German and American species, and this is done by eliminating the things that attract roaches to your homefood, moisture, and harborage sites.  

I will go over what you need to do briefly below, but be sure to read our detailed guide on the best way to get rid of roaches without an exterminator.

However, it is always advisable to get a professional pest control company to treat the infestation for you.  They will also tell you the following:

  • Remove all food sources – don’t leave food out.  Vacuum carpets and chairs where crumbs might have been dropped.  Remove or cover pet food and water bowls. 
  • Keep your home clean and sanitized and pay special attention to any drains, pipes, bathrooms, and basements that may be damp.
  • Check and seal with caulk all possible entry points on the ground level such as holes in foundations, gaps around windows and doors, and electrical outlets.
  • Place screens over drains 
  • Seal gaps around plumbing and repair leaky pipes and faucets. 
  • Install weather strips so they can’t squeeze through the gap under any doors. 
  • Clear window wells of leaves.
  • Keep the ground floor well ventilated – air conditioning or dehumidifiers are good for keeping down humidity levels 
  • Direct all downspouts away from the property 

Use Glue Traps to Find and monitor the Roaches 

Picture of cockroach sticky trap
Glue trap for monitoring cockroach population

The best way to detect and monitor a roach infestation is by using glue boards (sticky traps).

They should be placed flush against walls or surfaces close to where the roaches might be looking for water and/or food.   

Regularly inspect the traps so you can see where their population levels are highest and then you can use a roach gel bait to get rid of these filthy pests.    

Apply Pea-Sized Dots of Gel Bait

Professional exterminators use gel baits as they are a reliable form of pest control that comes in a syringe for spot treatment application.

Cockroach gel bait used by pest control professionals
Cockroach gel bait used by pest control professionals

As well as killing roaches when they eat the bait, it also kills them by contact.  In other words, a roach needs only be in contact with the gel for it to be carried back to the colony where it poisons the other roaches.

The gel bait should be applied in, or as close to, the harborage sites as possible in small pea-sized amounts.  

Apply Roach Powder/Dust or Boric Acid

Dust should be lightly puffed and used as a crack and crevice treatment in voids where you haven’t been able to apply the gel. 

The powder sticks to the body and legs of the roaches when they walk through it and gets carried back to the harborage area.  They will not walk through the powder if it is too thick. 

Roach powder can kill roaches for over a year as long as it doesn’t get wet. 

Don’t bother using a fogger as they don’t work and are more than likely to just cause the roaches to scatter to other areas.  

How to Keep Oriental Cockroaches Out?

You now know there are numerous ways the Oriental cockroach can get into your home but there’s no guarantee they won’t somehow get back in.  But make it hard for them and cover the groundwork by sealing all possible entry points and removing attractants such as water and food.  Keep monitoring the sticky traps and replace any gel bait if it’s dried out or eaten.

Oriental cockroaches are dangerous to have in your home because they live in filth and can spread harmful bacteria, so this is one pest you want to be rid of quickly and permanently.  

[1] https://www.who.int/

[2] Urban Insects and Arachnids: A Handbook of Urban Entomology

[3] https://extension.psu.edu/

I’ve been in the pest control industry helping people get rid of their unwanted pests for over 20 years, both in the UK and Canada.

As a licensed pest management professional, I’ve seen and treated just about every common household pest, insect, or rodent, you can think of. I’ve seen the damage caused when an infestation has been left too long and has become hard to get rid of.

For this reason, peststopsolutions.com was created. By having honest advice and the right guidance to hand, along with scientific evidence to back up claims, you are given information on the best eradication methods, as well as how to get rid of most pests yourself.