American Cockroach: Size, Flight, and Why It Got Indoors

What an American cockroach looks like

Size does most of the work here. Adults run 1.5 to 2 inches, or 35 to 53 mm, which makes this the largest cockroach that regularly gets indoors in the United States. Put it next to a German cockroach and the difference is roughly three to one.

The colour is a warm reddish brown across the body and wings, closer to chestnut than to the pale tan of the small kitchen species. Then check the pronotum, the shield that covers the head from above. A pale yellow band traces its outer edge, and on most individuals that band closes into a shape people describe as a figure of eight or a pair of rings. That marking is the clincher.

Wings overhang the tip of the abdomen, further on males than on females. The antennae are as long as the body, sometimes longer, and thread-fine. Underneath, a pair of short projections called cerci stick out at the rear, which is normal for cockroaches and worth not panicking about.

Not certain from a description alone? Upload a photo to our bug identifier by picture and check the result against this list.

American cockroach vs German cockroach

Here is the thing nobody says out loud. The big one is the easier problem.

German cockroaches live and breed indoors and never leave. You are fighting a resident population hidden in wall voids, one that reproduces in about 100 days and that increasingly resists both insecticides and sweet baits. American cockroaches mostly live outside, in sewers, drains, mulch and crawl spaces. They come in. That makes them a moisture and exclusion problem, and moisture and exclusion are things you can actually fix.

So if you have found one big reddish roach in the bathroom, you are in better shape than someone finding a dozen small pale ones in a kitchen cabinet. For that second problem, see our guide to the German cockroach.

Do American cockroaches fly?

Yes, and this is one of the few cockroach questions with a clean answer. Adults have full working wings and they will use them, unlike German cockroaches, which have wings and almost never fly.

The flight is not elegant. Most of it is a downward glide from a wall, ceiling or light fitting rather than a take-off from the floor. Warmth makes it far more likely, and above roughly 85°F they fly much more readily. That is why the flying-roach stories come mostly from Florida, Texas and the Gulf states in summer.

Nymphs cannot fly at all, because they have no wings until the final moult. So a large reddish roach that flew at you was an adult, and a smaller one that ran was probably not.

Nymphs and baby American cockroaches

A baby American cockroach looks like a smaller, duller version of the adult. Young nymphs are greyish brown and gain the reddish tone as they grow. They have no wings and no figure-eight marking early on, so size and colour do the identifying instead.

They pass through roughly 10 to 13 moults before reaching adult size, which is a lot more than the six a German cockroach needs. Each moult leaves a pale hollow shell behind, and a freshly moulted nymph is white for a few hours until the new cuticle hardens.

One practical note. A mid-sized American cockroach nymph is close in length to an adult German cockroach, and that is where most misidentification happens. Check the markings rather than the size: two dark lengthwise stripes mean German, and a pale band around the edge of the shield means American. Beetles cause the same trouble from the other direction, and our black beetle guide works through those.

Egg cases, and how fast they breed

The egg capsule is called an ootheca. On this species it is a dark brown purse roughly 8 mm long holding about 16 eggs, far fewer than the 30 to 48 a German cockroach packs into one case.

The behaviour differs too, and it matters. A female American cockroach carries the case for only a day or so, then glues it to a hidden surface and walks away. She often covers it with debris first. A female German cockroach, by contrast, carries hers until the eggs are nearly ready to hatch, which protects them from almost any treatment.

Over a lifetime a female may produce somewhere between a handful and 90 cases depending on conditions. That sounds alarming, but spread across a two-year life it is slow going compared with the German cockroach, which is why American cockroach numbers build far more gradually indoors.

How long American cockroaches live

Much longer than people assume. Development from egg to adult takes around 600 days in ordinary conditions, and warmth can shorten that considerably. Once mature, an adult typically lives about a year, and some records run well past that.

Set against the German cockroach, which reaches adulthood in about 100 days and lives 100 to 200 days after that, the contrast is stark. One species is built for speed of reproduction. The other is built to persist.

Where American cockroaches actually live

Not your kitchen counter, most of the time. This species wants warmth and damp, and it finds both in places you rarely look.

• Sewers and floor drains. The classic reservoir, and the reason for the nickname sewer roach.
• Basements, sump areas and crawl spaces, especially where water stands after rain.
• Steam tunnels and boiler rooms, which is why hospitals, schools and older institutions see them.
• Mulch, leaf litter and woodpiles stacked against the foundation.
• Tree holes and palm crowns in the South, where they live perfectly happily outdoors.
• Grocery stores, restaurants and bakeries, in the warm damp behind equipment.

They prefer temperatures around 84°F and do badly in the cold, which is why northern sightings cluster in heated basements and utility spaces rather than out in the yard. They are also nocturnal, so a daytime sighting out in the open usually means the insect was disturbed rather than that numbers are high.

Signs of American cockroaches

The evidence is bigger and coarser than a German cockroach leaves, which helps.

Because the droppings look so much like mouse droppings, that is the mistake worth avoiding. Roach droppings have flat ends and lengthwise ridges. Mouse droppings taper to a point at each end and crumble when dry. For dark specks that turn out to be neither, our guide to small black bugs in the house sorts through the rest.

Are American cockroaches dangerous?

They do not sting, and bites are rare enough to set aside. The real risk comes from where they have been.

Contamination comes first. An insect that spends its day in a sewer line and its night on a worktop moves organisms between the two. Spines on the legs pick up bacteria including Salmonella and E. coli, which is why food businesses treat a sighting as a serious event.

Allergens come second, and they have names. Researchers have characterised twelve allergen groups from this species, labelled Per a 1 through Per a 12, with more identified since. Two matter most in practice. Per a 10, a serine protease, shows IgE reactivity in over 80 percent of cockroach-sensitised patients. Per a 7 is a tropomyosin.

As for bites, they are possible and uncommon. If something is biting you at night, our bug bite identification guide covers the likelier culprits.

Palmetto bug, water bug, Bombay canary

This species collects nicknames, and the nicknames cause real confusion. Three come up constantly.

Palmetto bug is the messiest, because it is a regional label rather than a species. In Florida it usually means the Florida woods cockroach, Eurycotis floridana. In South Carolina it usually means the smokybrown cockroach, Periplaneta fuliginosa. Across the South more loosely, it often does mean the American cockroach. So the honest answer to “is a palmetto bug an American cockroach” is: sometimes, and you have to ask which insect the person means.

Water bug is misleading in a different way. A true water bug is an aquatic insect in a completely different order, and some of those genuinely do bite. When somebody indoors says water bug, they usually mean this cockroach or an oriental cockroach.

Bombay canary and ship cockroach are the old sailors’ names, and both point straight at how the species travelled. Ships carried it everywhere, and crews named it for the ports it came aboard from.

Where the American cockroach came from

Not America. The species is native to tropical Africa and the Middle East, and it reached the Americas the way most ship-borne pests did, as cargo nobody counted.

Maritime trade carried it west from the 17th century onward, the Atlantic slave trade included. The dating is unusually concrete for an insect: an egg case was recovered from the wreck of the San Antonio, a Spanish vessel that went down off Bermuda in 1625. So the species had already been making ocean crossings four centuries ago.

The name stuck anyway, exactly as it did with the German cockroach, which is also not German. Both were named for where Europeans happened to notice them rather than for where they evolved.

Four things that sound made up and are not

This species turns up in research far more than its reputation suggests. Four findings are worth knowing.

• It runs on two legs. Work at Berkeley in 1991 clocked it at 1.0 to 1.5 metres per second, roughly 50 body lengths a second. At those speeds it rears up and runs bipedally on its back pair of legs. Scaled to human size that is faster than any car most people own.
• Females can reproduce without males. Under some conditions they produce viable eggs by parthenogenesis, so an isolated female is not necessarily a dead end.
• A headless one survives for days. Cockroaches breathe through openings along the body rather than through a mouth and lungs, and their nervous system is spread through the body rather than centralised. A decapitated one eventually dies of thirst, not suffocation.
• China farms them by the billion. The species is reared at industrial scale for an extract used in traditional Chinese medicine. Whatever you make of the medicine, the farms are real and enormous.

Notice what is missing from that list. There is no heavy spraying programme, because the population you care about is not inside your walls. Get the damp down, close the gaps, and this species largely solves itself.

Pest control disclaimer. Photo-based identification can help, but it is not always perfect. For dangerous spiders, large infestations, or anything you are unsure about, contact a licensed pest control professional.