Egg to adult: about 600 days on average (UF/IFAS); egg case 57 days at 24.4 °C, 32 days at 30 °C (Ebeling); nymphs 160–971 days (Penn State). Adults: females 90–706 days (average 225), males 90–362 (average 200) at 29 °C (Ebeling). Size: about 4 cm (UF/IFAS). Flight: both sexes can fly (Texas A&M).
American cockroach lifespan
The american cockroach lifespan is the longest of any common pest cockroach. From the day its egg case is laid, an American cockroach usually spends well over a year growing up, and then lives for months to about two years as an adult. UF/IFAS puts it simply: "The life cycle from egg to adult averages about 600 days, and the adult life span may be another 400 days."
Laboratory records give the detail. At 29 °C (84 °F), adult females lived 90–706 days, averaging 225, and males 90–362 days, averaging 200 (Ebeling's review of earlier rearing studies). Penn State adds that a female can live up to 15 months "under ideal conditions". Put development and adulthood together and, at a typical 24 °C (75.2 °F) home, the shared model on this site gives:
| Who | Adult lifespan | Total from the egg |
|---|---|---|
| Female | 3–23.2 months (up to 1.9 years) | 10.1–57 months (up to 4.7 years) |
| Male | 3–11.9 months | 10.1–45.7 months (up to 3.8 years) |
| Not sure | 3–23.2 months (up to 1.9 years) | 10.1–57 months (up to 4.7 years) |
| Nymph of unknown age | — | 3–55.1 months (up to 4.6 years) still to go |
The range is wide because the nymph stage is: Penn State records anywhere from 160 to 971 days. The calculator above returns exactly the same numbers as the general cockroach lifespan calculator, because both pages use one data model.
How long do American cockroaches live as adults?
How long do American cockroaches live once they have wings? On average about seven months — 225 days for females and 200 for males in Ebeling's figures — but individual females have passed 700 days. UF/IFAS says adults "can live up to one year", and in that time an adult female produces "an average of 150 young". Females outlive males in every source we found, so a big, broad-bodied roach without long wing tips past its abdomen is likely the longer-lived sex.
No study we found tested adult lifespan at different temperatures, so the calculator keeps the adult ranges as published. What temperature does change is how fast the young grow — see the life cycle below.
American cockroach life cycle
The american cockroach life cycle has the same three stages as every cockroach — egg case, nymph and adult — but each one is long. At 24 °C (75.2 °F) the shared model gives an egg case of about 57 days and an average of 543 days as a nymph, for about 600 days from a new egg case to a new adult.
| Stage | Size | What it looks like | How long |
|---|---|---|---|
| Egg case (ootheca) | 8 × 5 mm; 14–16 eggs | brown when laid, black within a day or two | 57 days at 24.4 °C; 32 days at 30 °C |
| Nymphs | 3.5 mm when newly hatched | white just after hatching, then grey-brown; wingless | 160–971 days; 10–13 moults |
| Adult | 34–54 mm (about 1½ in) | reddish brown, pale band around the shield; long wings | 90–706 days (females), 90–362 (males) |
Sources: UF/IFAS EENY-141 and the UF/IFAS cockroach gallery (sizes, colours, moults), Ebeling (egg-case size, incubation at 24.4 and 30 °C, first-instar size, adult lifespans at 29 °C), Penn State (nymphs 160–971 days).
From mating to the first young
About one week after mating, the female produces her first ootheca, and at the peak of her reproductive period she may form two a week (UF/IFAS). Studies disagree on the total: UF/IFAS describes about one case a month for ten months, while one rearing study counted 15 to 90 cases per female, laid at about one a week (Ebeling). Each holds 14–16 eggs, and in Gould and Deay's cultures an average of 13.6 nymphs hatched from each of 534 cases (quoted by Ebeling).
The american cockroach egg case is "about 8 mm (1/3 in) long and 5 mm (3/16 in) high" (UF/IFAS) — larger and puffier than a German roach's. Unlike the German cockroach, the American female doesn't carry it to hatching: she drops it or glues it near food, usually within a day (Penn State), though UC IPM says some carry it for about six days. She "hides the oötheca with great care in a crevice, or buries it in soft wood or available debris" (Ebeling). For hatch dates from the day you find one, use the roach egg hatch timer.
American cockroach nymph
An american cockroach nymph hatches white, then turns greyish brown (UF/IFAS) and later reddish brown, with no wings until its final moult. Newly hatched nymphs are about 3.5 mm long (Ebeling). Counts of moults vary: the UF/IFAS gallery gives 10 to 13, and the UF/IFAS fact sheet says the number "varies from six to 14". That variation is one reason the nymph stage stretches from five months to more than two and a half years.
How temperature changes development
Only the egg case has been timed at more than one temperature: 57.4 days at 24.4 °C and 31.8 days at 30 °C (Ebeling). The table uses those two points; nymph development wasn't published by temperature, so it is held at Penn State's range and UF/IFAS's 600-day average.
| Temperature | Egg case to hatch | Egg case to adult (range) | Egg case to adult (average) |
|---|---|---|---|
| 22 °C (71.6 °F) | 57 days * | 7.1–33.8 months (up to 2.8 years) | about 600 days |
| 24.4 °C (75.9 °F) | 57 days | 7.1–33.8 months (up to 2.8 years) | about 600 days |
| 26 °C (78.8 °F) | 50 days | 6.9–33.5 months (up to 2.8 years) | about 600 days |
| 28 °C (82.4 °F) | 41 days | 6.6–33.2 months (up to 2.8 years) | about 600 days |
| 30 °C (86 °F) | 32 days | 6.3–32.9 months (up to 2.7 years) | about 600 days |
| 32 °C (89.6 °F) | 32 days * | 6.3–32.9 months (up to 2.7 years) | about 600 days |
* Outside the two measured temperatures, the nearest measured figure is used. The average total stays near 600 days because the nymph average (UF/IFAS) isn't temperature-adjusted.
How long do American cockroaches live indoors vs outdoors?
The lifespans above come from cultures with food and water. Where an American cockroach actually lives changes its odds, not its biology:
- Sewers and service tunnels. It is "found mainly in basements, sewers, steam tunnels, and drainage systems", and numbers can be enormous — "greater than 5,000 sometimes being found in individual sewer manholes" (UF/IFAS). Warm, wet and full of food, these are close to ideal rearing conditions.
- Commercial buildings. American cockroaches are "more common in commercial buildings than in residences" (UF/IFAS gallery), such as restaurants, food plants and large institutional buildings. In the northern United States they are found mainly in steam-heat tunnels and big buildings (UF/IFAS).
- Homes. "The American cockroach is rarely found in houses; however infestations can occur after heavy rain" (UF/IFAS). Most that turn up in a house have wandered in through floor drains, poorly sealed doors or roof soffits (Texas A&M).
- Outdoors. In warm regions they live in "moist, shady areas such as hollow trees, wood piles, and mulch", and "during the summer, alleyways and yards may be overrun" (UF/IFAS).
Indoors in a dry, clean house, food and especially water run short. Penn State's figures for adults are "two or three months without food but only about a month without water"; the cockroach without food and water timer has the full range by sex. Outdoors, cold limits them: in the North they survive winter mainly where buildings stay heated. So the honest answer to how long an American cockroach lives in your basement is "as long as the lab figures, if it can drink" — and a dripping pipe or a dry floor-drain trap can make all the difference.
Many people in the South call this species a palmetto bug, but that name also covers two other large cockroaches. If you're not sure which one you have, the palmetto bug identifier asks six quick questions.
American vs German cockroach
The american cockroach vs german cockroach comparison is a study in opposites. The American is about three times longer (44 mm against 14.5 mm, using the middle of each published range), takes seven to eight times as long to grow from egg to adult (about 600 days against 78 days at 24 °C) — and breeds far more slowly. That's why a German infestation in a kitchen explodes, while American cockroaches tend to arrive from outside or from drains.
| American cockroach | German cockroach | |
|---|---|---|
| Adult size | 34–54 mm (1⅜–2⅛ in); about 4 cm on average (UF/IFAS) | 13–16 mm (½–⅝ in) |
| Colour | reddish brown, pale or yellowish band around the shield behind the head | light brown, two dark stripes behind the head |
| Wings and flight | long wings; both sexes can fly, though not well | wings, but doesn't fly |
| Egg case | 8 × 5 mm, dropped or glued within about a day to 6 days | about 8 × 3 mm, carried until a day or two before hatching |
| Eggs per case | 14–16 | 30–40 (up to 48) |
| Egg cases per female | about 10 (UF/IFAS); 15–90 in one lab study | 4–8 |
| Egg case to hatch | 57 days at 24.4 °C; 32 days at 30 °C | about 28 days at room temperature |
| Nymph stage | 160–971 days; 10–13 moults | about 31 days (30 °C) to 87 days (20 °C); 5–6 moults |
| Adult lifespan | 90–706 days (females), 90–362 days (males) at 29 °C | 100–200 days; females about 200 |
| Where it lives | sewers, basements, steam tunnels, commercial buildings; outdoors in the South | indoors only: kitchens and bathrooms |
Sources: UF/IFAS (sizes, colours, eggs, cases, moults), Ebeling (egg cases, incubation, adult lifespans), Penn State (nymphs), Texas A&M (flight), Peterson et al. 2023 (German nymphs). For the German side in depth, see the German cockroach life cycle calculator and the German cockroach lifespan calculator.
American cockroach size
The american cockroach size is about 4 cm (1½ in) on average (UF/IFAS), with adults ranging from 34 to 54 mm, or about 1⅜ to 2⅛ inches (UF/IFAS gallery). Texas A&M calls it the largest cockroach in Texas, at 1½ to 2 inches. Males look longer because their wings reach 4–8 mm past the tip of the abdomen; females' wings don't. The newly hatched nymph is only 3.5 mm (Ebeling), so a single sewer or basement population holds roaches of every size from a few millimetres to over 5 cm.
Do American cockroaches fly?
Yes. Do American cockroaches fly? "Both the adult male and the female can fly" (Texas A&M), though UF/IFAS describes them as "poor to average fliers". They don't fly often: Ebeling couldn't make them fly by shaking them out of a container, but on a warm, sunny July day at 21 °C, some that were tossed into the air "flew gradually upward, some so far that they were lost from sight". Nymphs can't fly at all — only adults have working wings.
How this calculator works
Both modes use the shared cockroach data model on this site, so an American cockroach gets the same numbers here as on the general lifespan and life cycle pages:
- Lifespan mode: for an adult, the published adult range for the sex you pick (females 90–706 days and males 90–362 days at 29 °C, Ebeling; "Not sure" uses both). For a nymph of unknown age, the result runs from the adult range (if it is about to moult) up to a whole nymph stage plus the adult range. The total from the egg adds the egg case and the nymph stage.
- Egg case: straight-line interpolation between 57.4 days at 24.4 °C and 31.8 days at 30 °C (Ebeling), held at the nearest measured value outside that range, and flagged.
- Nymphs: Penn State's 160–971 days for the range; the average is UF/IFAS's 600 days from egg to adult minus the egg case. These aren't adjusted for temperature, because no temperature series was published.
- Life cycle mode: dates for the egg case, the nymph stage and the first adults, counted from the day the egg case was laid.
These are laboratory and extension figures for cockroaches with food and water. In real buildings, insecticides, predators and dry conditions cut many lives short.
Frequently asked questions
How long do American cockroaches live?
About 600 days from egg to adult on average, then up to a year or more as adults (UF/IFAS). At 24 °C our shared model gives 10.1–57 months (up to 4.7 years) in total.
What is the average lifespan of an American cockroach adult?
About 225 days for females and 200 for males at 29 °C, with females up to 706 days (Ebeling). Penn State says females can live up to 15 months.
How long is the American cockroach life cycle?
Egg to adult averages about 600 days (UF/IFAS): the egg case hatches in 31.8–57.4 days depending on warmth (Ebeling), and nymphs take 160–971 days (Penn State).
How many eggs does an American cockroach lay?
Each egg case holds 14–16 eggs, and a female produces an average of 150 young in her lifetime (UF/IFAS).
What does an American cockroach egg case look like?
About 8 mm long and 5 mm high, brown when laid and black within a day or two (UF/IFAS). See the roach egg hatch timer.
How big is an American cockroach?
About 4 cm (1½ in) on average, 34–54 mm overall (UF/IFAS) — the largest common pest cockroach.
Do American cockroaches fly?
Yes, both sexes can fly (Texas A&M), but they are poor to average fliers (UF/IFAS) and rarely do it.
What does an American cockroach nymph look like?
White right after hatching, then greyish to reddish brown and wingless; about 3.5 mm long at first (UF/IFAS; Ebeling).
Is an American cockroach the same as a German cockroach?
No. The American is about three times longer, lives far longer and lives mainly in sewers, basements and outdoors; the German is a small indoor kitchen pest.
Why do American cockroaches come into houses?
They live mostly outdoors and in sewers but move indoors in search of food or water (Texas A&M); infestations in houses can follow heavy rain (UF/IFAS).
Is an American cockroach a palmetto bug?
Often, yes — UF/IFAS and Texas A&M say it is often called a palmetto bug — but the name also covers the smokybrown and Florida woods cockroaches. Use the palmetto bug identifier.
How long can an American cockroach live without food?
Adults survive two or three months without food but only about a month without water (Penn State).
These calculators give estimates from laboratory, extension and husbandry figures, for education. Real cockroaches vary with strain, food, humidity and temperature. Cockroach droppings, saliva and shed skins contain allergens that can trigger asthma, especially in children (CDC; Penn State) — for health questions, talk to a doctor. For a heavy infestation, contact a licensed pest professional or your local extension service. We name no products and give no pesticide doses.