American Cockroach: How to Identify It and Spot the Signs of an Infestation

What Is an American Cockroach?

The American cockroach (Periplaneta americana) is the largest common cockroach, a reddish-brown roach about 4 cm long that lives in sewers, drains and damp basements. It is among the common species in Canada, according to Orkin Canada, and the City of Winnipeg lists it among the cockroach species found in the city, alongside the German and Oriental cockroaches. Unlike the German cockroach, it is less likely to set up a lasting population inside a house, so seeing one is often a clue about a drain or moisture problem. For every other roach topic, from prevention to treatment, start from our cockroach guides.

What Does an American Cockroach Look Like?

An American cockroach looks like a large, shiny, reddish-brown roach with a pale brown or yellowish band around the edge of the shield behind its head (the pronotum), according to UF/IFAS. Some people notice a yellowish figure 8 pattern on that shield. Adults usually have long antennae and fully developed wings that cover the back. Young cockroaches (nymphs) are smaller, usually greyish brown and wingless, and they tend to turn reddish brown after their first few molts (Penn State Extension).

How Big Is an American Cockroach?

An American cockroach measures about 4 cm (1.5 inches) long on average, according to UF/IFAS, and may reach up to about 5 cm (2 inches), according to UC IPM and the City of Winnipeg. That makes it about two to three times longer than a German cockroach. In males, the wings usually extend past the tip of the abdomen, so males look a little longer than females.

Can American Cockroaches Fly?

American cockroaches can fly, but usually only short distances. Both males and females have working wings once they reach adulthood. Penn State Extension notes that they rarely fly in northern areas, so in a Canadian home you are more likely to see one running fast across the floor than flying.

How Is an American Cockroach Different From a German Cockroach?

An American cockroach is much bigger than a German cockroach. Health Canada describes the German cockroach as about 1.3 cm to 1.6 cm long, tan to light brown, with two dark parallel stripes behind the head, and it generally does not fly. Health Canada calls it one of the most common household cockroaches in the world, and it usually lives and breeds indoors. If you are not sure which roach you have, our cockroach identification guide compares the species found in Canada.

How Is an American Cockroach Different From an Oriental Cockroach?

An American cockroach is reddish brown with full wings, while an Oriental cockroach is black or very dark reddish brown and has short wings or only wing stubs. The City of Winnipeg gives the Oriental cockroach a length of about 25 to 35 mm. UC IPM adds that Oriental cockroaches cannot climb smooth vertical surfaces and do not fly. Both species like damp basements and drains, so colour and wings are the easiest way to tell them apart.

Where Do American Cockroaches Live in Canada?

American cockroaches live in warm, humid places: sewers, steam tunnels, boiler rooms, floor drains, crawl spaces and basements (Penn State Extension). UC IPM says they prefer temperatures usually above 28°C (82°F), which is why, in Canada, they stay in heated spaces such as sewer systems, large institutional buildings and the basements of restaurants, bakeries and grocery stores. UF/IFAS notes that they are rarely found in houses, but they may move into ground floors and basements from sewers, especially where pipes are damaged or drain traps are faulty.

How Long Do American Cockroaches Live?

American cockroaches can live up to about one year as adults, according to UF/IFAS, and Penn State Extension reports that females may live up to 15 months under ideal conditions. They are tough on food but not on water: adults may survive two or three months without food, but often only about a month without water. This is why moisture control matters so much more than crumbs for this species.

Are American Cockroaches Dangerous?

American cockroaches are a hygiene risk rather than a physical threat. They travel through sewers and garbage, so they can spread food-poisoning bacteria such as Salmonella and Shigella (UC IPM), and UF/IFAS reports that many species of disease-causing bacteria, viruses, fungi and protozoans have been found on field-collected American cockroaches. Their droppings and shed skins contain allergens that can cause sneezing, watery eyes, asthma symptoms and possibly skin rashes (Penn State Extension), and the University of Kentucky notes that many people are allergic to them. They can bite, but they rarely do.

What Are the Signs of American Cockroaches?

Signs of American cockroaches can include live or dead roaches, small ridged droppings, dark egg cases, cast skins and a musty smell, usually near water. UC IPM lists the same clues for all cockroaches: droppings, cast skins, egg cases and live or dead insects. Check basements, laundry rooms, bathrooms, under sinks and around floor drains first.

Live Cockroaches

Live cockroaches are the clearest sign. American cockroaches avoid light and are most active at night, so you usually see them when you turn on a basement or bathroom light and they run for cover. During the day they often rest near water pipes, sinks, bathtubs and toilets (UF/IFAS). Seeing them in daylight is a warning sign: with cockroaches, daytime activity may point to a large population or a shortage of food or water (Penn State Extension).

Droppings

Droppings from American cockroaches are usually small, dark and blunt at both ends, with ridges along the sides, according to the National Pest Management Association (PestWorld). That shape helps you tell them apart from mouse droppings, which usually have pointed ends. You may also find dark spots or smears on shelves, along baseboards and in corners where cockroaches rest (UC IPM).

Egg Cases

Egg cases (oothecae) are a sure sign that cockroaches are breeding nearby. An American cockroach egg case is about 8 mm (1/3 inch) long, brown when laid and usually black within a day or two, and often holds around 16 eggs (UF/IFAS). Females glue them to hidden surfaces close to food, often in basements, laundry rooms, kitchens and behind appliances. The young usually hatch after about six to eight weeks.

Cast Skins

Cast skins are the empty shells nymphs leave behind each time they molt. UC IPM lists them among the signs of an infestation. They collect in the same hiding spots as droppings: behind appliances, in cabinet corners, near pipes and in cluttered basement storage.

Musty Odour

A musty odour is a sign of a larger population. American cockroaches release a pheromone that some people describe as musty, and Penn State Extension notes that high populations may produce a characteristic smell in the infested area. If a basement or storage room smells stale even after cleaning, check it with a flashlight at night.

Dead Cockroaches

Dead cockroaches, especially several in one spot, mean live ones are nearby. Look in basements, behind the washer and dryer, under sinks and near floor drains. For the signs that apply to every species, including the German cockroach, see our guide to cockroach infestation signs.

Why Is There an American Cockroach in Your House?

An American cockroach in your house usually came up from a drain, a sewer line or a damp basement rather than from dirt in your kitchen. Health Canada points out that cockroaches in a home do not necessarily mean the home is unclean. Finding the entry point is what stops them.

Drains

Drains are the most common way in. UC IPM explains that American cockroaches move from sewers into the ground floor of buildings, especially where pipes are damaged, screens are missing or drain water traps are faulty. A floor drain or a guest bathroom that is rarely used can dry out, leaving an open path from the sewer. Our guide on how to stop cockroaches from coming up the drain covers this step by step.

Moisture

Moisture is what keeps American cockroaches in your home once they are inside. Leaky pipes, sweating water heaters, damp crawl spaces and wet basement floors give them the water they need. Utah State University notes that they often favour warm, moist spots under sinks, in bathtubs and in furnace and boiler rooms.

Weather

Weather changes push American cockroaches indoors. Utah State University says they may move inside during hot weather and flooding, UF/IFAS links some house infestations to heavy rain, and Penn State Extension notes that in northern areas they may travel between buildings during warm months. In Canada, that makes sightings in houses more likely in summer or after a storm.

Does One American Cockroach Mean an Infestation?

One American cockroach does not always mean an infestation. A single roach that wandered in from a drain or from outside is common, especially in summer. It does mean you should check: set sticky traps for about a week, look for droppings and egg cases, and see whether more show up. Our article on how many cockroaches is an infestation explains how to read what you find.

What Should You Do About an American Cockroach Infestation?

An American cockroach infestation is handled by finding where the roaches come in, removing water and shelter, and using baits rather than sprays. Health Canada stresses that cleaning and pesticides should be used together, because pesticides alone will not succeed.

Sticky Traps

Sticky traps can show roughly how many cockroaches you have and where they come from. Place them along walls near floor drains, exterior doors, sinks and the water heater, and check them daily. UC IPM recommends checking traps until you find where the most cockroaches are caught, and Penn State Extension notes that one week of trapping usually gives enough information.

Drain Traps

Drain traps that stay full of water help block the path from the sewer. Run water in spare sinks, tubs and floor drains regularly so the U-traps are less likely to dry out (PestWorld). Health Canada also suggests covering vents, open pipes and drains with fine mesh screen.

Leaks

Leaks are worth fixing right away, because an American cockroach often survives only about a month without water. Repair dripping taps and pipes, dry out damp basements with a dehumidifier, ventilate crawl spaces and do not leave water standing in sinks or buckets overnight.

Sealing

Sealing closes the gaps American cockroaches use to get in. It helps to caulk cracks in foundations and walls, seal openings around pipes, and add door sweeps and weather stripping to doors that lead outside or to the garage (UC IPM, Utah State University). For a full routine, see our guide on how to prevent cockroaches.

Baits

Baits are often the most useful product against American cockroaches, because roaches eat them and die later in their hiding spots (University of Kentucky). Penn State Extension lists fipronil, boric acid and abamectin among the bait ingredients that work when placed where cockroaches hide. Health Canada notes that bait stations kill about 48 to 96 hours after the insect eats the bait. Choose a product labelled for American or large cockroaches, check for a PCP number on the label (it means Health Canada has registered the product), follow the directions and keep baits out of reach of children and pets. Our picks for the best cockroach killer can help you compare options.

Dusts

Dusts such as boric acid (professional use only in Canada), silica aerogel and diatomaceous earth add control in places baits cannot reach. Penn State Extension advises applying them lightly into cracks and crevices, and Health Canada notes that diatomaceous earth stays active only while dry and warns not to breathe it in. Keep all dusts away from children and pets.

Why Sprays Make It Worse

Sprays and foggers can make an American cockroach problem worse because, as UC IPM notes, they may scatter the roaches and often do not reach the crevices where they hide. Penn State Extension says residual sprays and aerosol foggers are often of little value against this species, UC IPM notes that sprays alone are not an effective long-term solution, and the University of Kentucky says foggers are seldom effective. Spraying near baits also stops roaches from eating them.

When to Call a Pest Control Professional

Calling a licensed pest control professional makes sense when sticky traps keep catching cockroaches after a few weeks, when you find egg cases, or when the roaches come from a shared sewer line or another unit. The City of Winnipeg notes that cockroaches should be controlled throughout a building, not just in one area, and that repeat applications are often needed. If you rent, tell your landlord right away: Manitoba advises tenants and landlords to act quickly to limit the spread. To understand the process, read our guide to cockroach pest control, and you can get a quote from a recommended local exterminator through Pest Agent's referral form.