# Oriental cockroach (Blatta orientalis) > A dark, slow-moving synanthropic cockroach often found in cool, damp places around buildings and sewer systems. Source: https://insectscanner.com/species/oriental-cockroach/ (updated 2026-10-10) ## Is it dangerous? **Contaminant.** Oriental cockroaches do not bite or sting and are not venomous. The main human health concern is contamination: they can carry bacteria, parasites and allergens on their bodies and in feces, potentially triggering foodborne illness or allergic reactions. If you find one in food, discard contaminated food and clean surfaces with detergent and a disinfectant. For heavy infestations seek professional pest control. **Pets:** They are not poisonous to pets, but pets that eat roaches may acquire parasites or stomach upset. Prevent pets from eating roaches and remove infestations to avoid repeated exposure. ## Quick facts - Scientific name: Blatta orientalis - Also called: Black beetle, Waterbug - Order: Blattodea (Cockroaches and termites) - Family: Blattidae (Cockroaches) - Size: Males about 18-25 mm; females about 25-32 mm (body length) - Colours: Dark brown, Black, Reddish brown (young nymphs) - Habitat: Cool, damp and shaded areas around human buildings: basements, crawlspaces, drains, sewers, leaf litter and compost piles. - Range: Originally from the Middle East or Mediterranean region; now widespread worldwide in temperate to subtropical regions and commonly established in cities globally. - Active: Mostly nocturnal; active year-round in warm buildings, outdoors in temperate climates mainly spring to autumn. - Lifespan: Adults live several months to about one year under favorable conditions. - Effect on plants: Detritivore - Pest: yes ## Overview Blatta orientalis, the Oriental cockroach, is a medium-large roach species closely associated with human structures. It prefers cool, damp, shaded habitats such as basements, crawlspaces, drains and sewers. Unlike some other pest cockroaches it is not a strong climber and is commonly found at ground level. Oriental cockroaches are omnivorous scavengers and can contaminate food and surfaces, making them a public-health nuisance rather than a venomous threat. ## How to identify it Adults are robust, oval, and relatively slow-moving. Adult males are about 18-25 mm long and have short wings that cover most of the abdomen but do not support flight; females are larger (about 25-32 mm), broader, and have only tiny wing pads. Both sexes are uniformly dark brown to nearly black, often with a somewhat glossy appearance. Nymphs are similar in shape but smaller and lighter brown until they darken with successive molts. - Uniform dark brown to black, glossy, oval body about 18-32 mm long. - Relatively slow-moving and poor climber; often found at ground level or in drains. - Males smaller with short wings covering most of abdomen; females larger and broader with only tiny wing pads and no flight. - Found in cool, damp locations such as basements, crawlspaces, leaf litter, compost and sewers. ## Lookalikes - **American cockroach** (Periplaneta americana): Larger (up to 30-40 mm), reddish brown with a pale margin behind the head and fully developed wings; better climber and more likely in kitchens and upper floors. - **German cockroach** (Blattella germanica): Smaller (12-16 mm), light brown with two dark parallel stripes on the pronotum; fast-moving and commonly found in kitchens and food preparation areas. - **Brown-banded cockroach** (Supella longipalpa): Smaller and slender with pale bands across the wings and abdomen; prefers warmer, drier indoor locations and higher surfaces. ## Life cycle - **Egg (ootheca):** Females produce an ootheca (egg case) containing about 16-24 eggs and commonly deposit it in protected, damp locations. Egg cases hatch in 1-2 months depending on temperature. - **Nymph:** Nymphs are wingless, smaller versions of adults; they pass through multiple molts over several months, gradually darkening and developing adult form. - **Adult:** Adults have reduced wings (males with short wings, females with very reduced wings) and are capable of mating and producing more oothecae; development to adulthood typically takes several months. ## Diet and predators - Young eat: Decaying organic matter, detritus, faeces, leftover food and other household organic debris. - Adults eat: Omnivorous scavengers: decaying plant and animal matter, garbage, pet food, drains and sewers; they will eat a wide variety of organic material. - Predators of the young: Generalist predators: spiders, ants, centipedes, beetles and small vertebrates. - Predators of adults: Birds, amphibians, small mammals, some predatory insects and spiders; in buildings they have few predators. ## Effect on plants and gardens Oriental cockroaches feed on decaying organic matter and are not primary plant pests; they may occasionally feed on seedlings or tender plant material but generally have neutral impact on gardens. ### How to get rid of it Reduce moisture and hiding places: fix leaks, ventilate basements, seal cracks and gaps at ground level, store food in sealed containers and remove organic debris. Clean drains and traps. Use sticky traps or bait stations labelled for cockroaches for monitoring and control. For large or persistent infestations, hire a licensed pest control professional who can apply baits, insect growth regulators or targeted residual treatments. ## Where and when to find it Look at ground level in basements, crawlspaces, drains, under mulch, compost piles and near sewer openings. Nymphs and adults hide in cracks and crevices during the day and emerge at night. - Best time: Night-time is best for observation; indoors they can be seen year-round, outdoors mainly spring through autumn in temperate regions. - Tips: Turn on a flashlight at night and check damp areas and drain covers. Sticky traps placed along baseboards and near suspected entry points are useful for detecting presence. ## Fun facts - Called a 'waterbug' in some regions because it tolerates damp, sewer-like habitats and is commonly found near drains. - Oriental cockroaches are less able to climb smooth vertical surfaces than many other pest roaches, so they are most often encountered at ground level. - They are one of the common synanthropic cockroach species that spread worldwide alongside human settlements. ## Frequently asked questions ### Do Oriental cockroaches bite? No, they are not known to bite people. They are primarily a contaminant and nuisance rather than a biting pest. ### Are Oriental cockroaches dangerous? Only mildly. They are not venomous, but can spread bacteria and allergens by contaminating food and surfaces; heavy infestations can pose health concerns. ### Why do I have Oriental cockroaches in my house? They are attracted to cool, damp, dark places and food sources. Basements, crawlspaces, drains, compost and clogged gutters provide ideal conditions. ### How do I get rid of Oriental cockroaches? Reduce moisture and hiding places, seal entry points, clean up food and organic debris, use bait stations and traps, and consult a professional for persistent infestations. ### Can Oriental cockroaches fly? No. Adults have shortened wings and are not capable of sustained flight. ### Where do Oriental cockroaches live outdoors? They live in shaded, damp areas such as leaf litter, compost heaps, under stones, sewers and storm drains, especially in temperate and subtropical regions. --- More about this species: [iNaturalist](https://www.inaturalist.org/taxa/154213), [Wikipedia](https://en.wikipedia.org/wiki/Oriental_cockroach). Identify insects and spiders from a photo with the Insect Scanner iPhone app: https://apps.apple.com/app/id1543946563?pt=126685406&ct=web-markdown&mt=8 Identification from photos is never certain: don't handle insects you can't identify, and get medical advice for bites, stings or allergic reactions.