Blatta orientalis
Found a large, dark cockroach in your home or workplace?
Seeing a cockroach can be unsettling. You might also have found droppings that look like mouse droppings, or noticed activity around a drain, cellar, kitchen or storage area.
Oriental cockroaches are often associated with damp, cooler places, but they can also be found inside homes and commercial buildings, including flats and HMOs. If you are unsure what you have seen, we can assess it and explain the next step.
What does an Oriental cockroach look like?
The Oriental cockroach is usually dark brown to black, with a broad, flattened body. Adults are generally around 20 to 24 mm long. Females have short wing cases and males have longer ones, but neither normally flies.
Young cockroaches, called nymphs, are smaller and do not have fully developed wings. Their colour changes as they grow. Oriental cockroaches can be confused with other cockroach species, so a photograph or specimen can help with identification.
Why do I have Oriental cockroaches?
Oriental cockroaches favour damp, sheltered areas and can feed on a range of food scraps and organic material. They are often associated with drains, cellars, basements, service spaces, waste areas and places where moisture is present.
They may enter through gaps around pipes, drains, doors or other openings. In some cases, they may also arrive with stored goods or packaging.
Finding one does not automatically show where it came from or how widespread the activity is. An inspection can help identify likely routes and conditions that may be supporting it.
Why cockroaches need to be dealt with
Cockroaches can move between waste, drains and areas where food is stored or prepared. They can contaminate food and surfaces with their bodies and droppings, and may carry bacteria.
That can be a particular concern in kitchens, food businesses and shared buildings. An inspection helps establish what has been found and whether activity may involve more than one room or a shared area.
Oriental cockroach droppings
Oriental cockroach droppings can look like small, dark pellets and may be mistaken for mouse droppings. Larger cockroach droppings can have fine grooves along their length, but this can be difficult to confirm without close examination. Droppings alone are not a reliable way to identify the pest.
If you find droppings, take a photograph and note where you found them. Avoid handling them directly.
The life cycle of the Oriental cockroach
Oriental cockroaches develop through three stages: egg, nymph and adult.
The female produces an egg case, called an ootheca, and deposits it in a sheltered place. The young hatch as nymphs and grow through a series of moults before becoming adults. Development can take many months and varies with temperature and conditions.
Because egg cases may be hidden and can hatch after treatment, one visit may not resolve an infestation. Further inspection or treatment may be needed, depending on what is found.
How Guardian deals with Oriental cockroaches
The right approach depends on the building, the level of activity and where the cockroaches are harbouring. We assess the problem and look for the conditions and access points that may be contributing to it.
For many Oriental cockroach problems, professional gel treatments are a practical option. Depending on the site and the product used, treatment may be possible while people remain in the building. We will explain any precautions needed before work begins.
Other options may include monitoring, physical control or a different targeted treatment. Some products require people to leave the treated area, so we will explain this in advance if it applies.
Cockroach control often needs follow-up. New nymphs may hatch after the first treatment, so we will explain whether further visits are likely and what to expect.
For flats and HMOs, we will consider whether activity may involve shared areas or more than one part of the property, and explain what access or further investigation may be needed.
After the visit, the instructing landlord or agent receives a digital report explaining what we found, what work was carried out and whether further visits or action are recommended.
What can I do if I find an Oriental cockroach?
If possible, take a clear photograph or safely contain a specimen so it can be identified. Note where and when you found it, and whether you have seen any others.
Keep food sealed and clean up food debris. If you find activity near a leak, drain or damp area, mention that when you contact us. Avoid using household sprays before identification, as they may disturb the cockroaches and make it harder to assess where they are hiding.
Frequently asked questions
Are Oriental cockroaches dangerous?
They can contaminate food and surfaces, so it is sensible to take sightings seriously, especially in food preparation areas. If you have found one, we can help identify it and advise on the next step.
Can Oriental cockroach droppings be mistaken for mouse droppings?
Yes. The droppings can look similar. A close examination may show grooves on cockroach droppings, but a photograph or sample may still need professional identification.
Will one treatment get rid of them?
Not always. Egg cases may hatch after treatment, and further visits may be needed to check for new activity and treat it where necessary.
Do I need to leave the building during treatment?
That depends on the treatment and product used. Some gel treatments may allow people to remain in the building, while other treatments may require the area to be vacated. We will explain what applies before carrying out the work.
Can cockroaches spread between flats or rooms?
They may move through shared spaces or service routes. We will assess the reported activity and explain whether access to another area or further investigation may be needed.
Speak to Guardian Pest Control
Tell us what you have seen and where you found it. We will assess the information, explain the options and recommend the most sensible next step.
