How Long Do Roach Eggs Take to Hatch? Egg Case & Gestation Timer

How long do roach eggs take to hatch?

How long do roach eggs take to hatch? Roughly two weeks to three months, depending on the species and how warm it is. Cockroach eggs are never laid one by one: they sit in rows inside a hard egg case (an ootheca), and the whole case hatches at once. At 24 °C (75.2 °F), the shared model on this site gives:

• German cockroach: about 28 days, while the mother carries the case (Gould & Deay 1940; Penn State) — and only 14 days at 35 °C (Ross 1929, both quoted by Ebeling). UC IPM calls it "the 30-day incubation period".
• American cockroach: about 57 days at 24.4 °C, 31.8 days at 30 °C (Ebeling). UF/IFAS says nymphs "emerge from the egg case after about six to eight weeks".
• Oriental cockroach: about 67 days — between 81 days at 21 °C and 42 days at 29.5 °C (Ebeling; UF/IFAS).
• Brown-banded cockroach: about 83 days — 95.6 days at 22.5 °C and 49 days at 28 °C (Ebeling), the slowest of the indoor species.
• Florida woods cockroach (a palmetto bug): about 48 days at 30–36 °C (UF/IFAS IN915).
• Dubia and Madagascar hissing cockroaches don't leave eggs anywhere: the female keeps the egg case inside her body and gives birth to live nymphs (see gestation below).

So how long do cockroach eggs take to hatch has one short answer — about a month for the German cockroach that infests most kitchens — and a longer one for the big outdoor species, whose cases can sit for two or three months. The hatch timer above turns that into dates: pick the species, whether the case was loose or still on the female, the day you found it and your room temperature.

How long does it take for cockroach eggs to hatch at different temperatures?

Warmth speeds hatching dramatically. How long does it take for cockroach eggs to hatch at each temperature, from the measured points in the scientific literature (straight-line between them):

* Outside the measured temperatures for that species, so the nearest measured figure is used: German below 24.4 °C (held at about 28 days, the room-temperature figure), American below 24.4 °C or above 30 °C, Oriental below 21 °C or above 29.5 °C, brown-banded below 22.5 °C or above 28 °C, and Florida woods outside 30–36 °C. German development wasn't measured below 20 °C, and at 15 °C none of the nymphs survived (Peterson et al. 2023). These are the same egg-case figures used by the cockroach life cycle calculator.

The same numbers answer how long does it take a roach egg to hatch, how long does it take for roach eggs to hatch and how long does it take cockroach eggs to hatch: there is no separate figure for a single egg, because all the eggs in a case develop and hatch together.

How long does it take roaches to hatch after the case is dropped?

That depends on who dropped it. How long does it take roaches to hatch from a case you find on the floor?

• A loose German case: almost immediately. The female carries her case "for as long as a month, until a day or two before the eggs are ready to hatch, then drops it anywhere" (Ebeling), and in one study 92.9% of nymphs emerged within 24 hours of the case being dropped (Wright 1968, quoted by Ebeling). Nymphs often hatch while it is still attached (UF/IFAS).
• Any other species: anywhere from a few days to the full incubation, because she drops or glues it within hours or days of forming it — 12 hours to five days for Oriental females (UF/IFAS), 24–36 hours for brown-banded (Ebeling), within a day (Penn State) or about six days (UC IPM) for American females.

That's why the timer gives a window rather than a date: unless you saw it laid, the case could be fresh or nearly ready — so how long does it take cockroaches to hatch from a found case is "any day up to the full incubation", and how long does it take for roaches to hatch from a case you watched being laid is the full incubation in the table above. A case still on the female is the exception — it is fresh, so its window starts close to the full incubation. And how long does it take for cockroaches to hatch once they start? Quickly: nearly all of a German case's nymphs emerged within a day in Wright's study, and freshly hatched American nymphs are white before they turn grey-brown (UF/IFAS).

Cockroach egg cases (oothecae) explained

A cockroach egg case (ootheca) is a hardened purse or bean-shaped capsule that the female builds around a double row of eggs at the tip of her abdomen. It shields the eggs from drying out and from insecticides (Ebeling). Every species' case differs in size and colour:

Sources: Ebeling (sizes for German, American, Oriental and brown-banded; colours), UF/IFAS (eggs per case; Florida woods case), Penn State and UC IPM (carrying and gluing), Animal Diversity Web and Wikipedia's summary of Alamer (2013) for the internal cases of hissing and dubia cockroaches.

What do roach eggs look like?

What do roach eggs look like? You almost never see the eggs themselves — only the case. Look for a small, hard, brown-to-black capsule — "small, brown, bean-shaped", as the University of Kentucky describes them:

• German: about 8 × 3 mm, light brown and purse-shaped, often still sticking out of the female's abdomen (UF/IFAS; Ebeling).
• American: 8 × 5 mm — plumper — brown when laid and black "in a day or two" (UF/IFAS; Ebeling).
• Oriental: 10 × 5 mm, the largest of the common indoor species, "reddish brown and soft" at first, then "black, hard, and brittle" (Ebeling).
• Brown-banded: about 4 × 2.5 mm, "the smallest of the common domiciliary cockroach oöthecae", yellowish to reddish brown (Ebeling).
• Florida woods: 13–16 mm long, darkening "from reddish brown to black", with 18–24 saw-like teeth along its upper edge (UF/IFAS IN915).

German females that are carrying a case are easy to spot: the light brown case sticks out from the tip of the abdomen, and "sometimes the egg case hatches while it is still being carried by the female" (UC IPM).

Why egg cases are so tough

The case is built to stop water loss. "The oöthecae of other species are remarkably resistant to desiccation," writes Ebeling: in Roth and Willis's experiments, eggs in Oriental cases kept at 0% humidity still hatched, after about 46 days. The German cockroach is the exception. Its eggs depend on the mother to stay moist — German cases placed with their front end on wet filter paper gained weight (Roth & Willis 1955) — and "the eggs become desiccated if the oötheca is removed from the female any time before its normal time to drop" (Ebeling). That's why the German female carries hers for weeks — and why German eggs are the hardest to find.

Cockroach gestation period by species

Strictly speaking, most cockroaches don't have a pregnancy. When people ask about the cockroach gestation period, they usually mean the whole wait from the female forming an egg case to the nymphs coming out — forming it, carrying it, and incubation once it's put down. The explainer mode of the timer shows that as a timeline. At 24 °C (75.2 °F):

Sources: German — Gould & Deay 1940 and Ross 1929 (via Ebeling), UF/IFAS. American, Oriental, brown-banded — Ebeling, UF/IFAS, Penn State, UC IPM. Florida woods — UF/IFAS IN915. Smokybrown — the cases are glued soon after forming, but no incubation figure we could verify. Dubia — DartFrog.pet (feeder supplier: about 28 days) and Wikipedia's summary of Hintze-Podufal & Vetter (1996: 48–64 days at 26 °C). Madagascar hissing — Animal Diversity Web and Oakland Zoo (about two months).

Roach gestation period: what the word means for cockroaches

The roach gestation period is only a true pregnancy in a few species. Three strategies exist among the cockroaches on this site:

1. Drop it early (American, Oriental, brown-banded, smokybrown, Florida woods). The case is glued or hidden within hours or days and the eggs develop on their own, so almost all of the "gestation" is incubation.
2. Carry it outside (German). The case stays attached to the tip of her abdomen for about four weeks, which keeps the eggs from drying out, and is dropped a day or two before hatching (Ebeling). The German female is carrying, not pregnant — the case is outside her body.
3. Keep it inside (Madagascar hissing and dubia cockroaches). These are ovoviviparous: "The females carry the ootheca, a long yellowish egg case, internally and they release the young nymphs after the eggs have hatched" (Animal Diversity Web). For hissers gestation is about two months, with 15–40 nymphs. Dubia roaches are described as partially ovoviviparous, with pregnancies of 48–64 days at 26 °C in one study and about 28 days according to a feeder supplier; litters are 20–40 nymphs. For colony planning, see the dubia roach life cycle and colony planner.

How many eggs are in a roach egg case?

How many eggs in a roach egg case? Texas A&M's answer is "12 to 36 eggs at a time, depending on the species" — and the German cockroach can go higher. Not every egg hatches, so the useful figure is how many nymphs come out:

Sources: UF/IFAS (eggs and cases for German, American, Oriental, smokybrown, Florida woods; American lifetime young), Penn State (German up to 48), Gould & Deay 1940 via Ebeling (29.9 German and 13.6 American nymphs per case), Ebeling (brown-banded), University of Kentucky ("up to 40 with the German cockroach, 15-20 with other varieties"), DartFrog.pet and Wikipedia (dubia), Animal Diversity Web and zoos (hissing). Lifetime totals are simple multiplications of the published ranges, not measured counts.

The German cockroach's big batches, protected by its mother until hatching, are what make it the hardest species to control: the University of Kentucky warns that "a single mated female can produce thousands of new cockroaches in less than a year". The German page's population estimate shows how fast that adds up — see the German cockroach life cycle calculator.

Where roaches lay eggs and how to find them

Where do roaches lay eggs? Close to food, water and shelter, in places you rarely look:

• German cockroaches don't choose a spot at all until the last moment: the female drops the case "anywhere" a day or two before it hatches (Ebeling) — usually in the same warm cracks near kitchen and bathroom water and food where German cockroaches spend about 75% of their lives (Texas A&M).
• American cockroaches deposit cases "near a source of food, sometimes gluing it to a surface with a secretion from her mouth" (UF/IFAS); she "hides the oötheca with great care in a crevice, or buries it in soft wood or available debris" (Ebeling). Outdoors she prefers "moist, concealed oviposition sites" (UF/IFAS).
• Oriental cockroaches drop theirs "in a warm sheltered environment where food is readily available" (UF/IFAS) — basements, crawl spaces and floor drains.
• Brown-banded cockroaches glue theirs to surfaces in the warm, dry rooms they prefer, where the eggs incubate for several weeks (UC IPM).
• Florida woods cockroaches glue theirs to the substrate outdoors, "such as a decaying log" (UF/IFAS IN915).

To find them, UC IPM advises: "Look for egg cases glued to undersides of furniture, in refrigerator and other appliance motors, boxes, and other items. Remove any that you find." A good flashlight helps, and so do sticky monitors, which show where roaches gather (Texas A&M). German cockroach droppings "look like crushed pepper" and collect where roaches congregate (Texas A&M) — the best places to search.

How to get rid of roach eggs without chemicals

How to get rid of roach eggs without spraying? The extension guides list four non-toxic steps:

1. Vacuum. "Vacuuming also removes cockroaches, shed skins, and egg cases, reducing overall cockroach numbers" (UC IPM). Use the crevice tool along baseboards, cabinet hinges, behind appliances and under sinks.
2. Remove the cases you find from furniture, appliance motors and boxes (UC IPM).
3. Clear hiding places. Get rid of stacks of cardboard, paper bags and newspapers, or store them in sealed plastic bags (University of Kentucky).
4. Seal cracks and gaps around pipes, cabinets and baseboards so the next generation has fewer places to hide (CDC; University of Kentucky).

Do roach eggs survive bug spray?

Do roach eggs survive bug spray? Usually, yes. "Oöthecae also effectively protect the enclosed eggs from insecticides. Not until the eggs are hatched and the nymphs leave the protection of the oötheca and crawl over the insecticide residue are they subjected to the effects of an insecticide treatment" (Ebeling). Sprays and foggers also don't reach the cracks where cases are hidden: the University of Kentucky does not recommend foggers, and UC IPM says sprays give only "a quick, temporary knockdown". The way to deal with eggs is to remove the cases you can find and let the nymphs that hatch meet baits and monitors when they come out.

Why roaches keep appearing after treatment

Because the egg cases were already there. Any case formed before treatment keeps developing, protected from insecticide, and hatches on its own schedule — days to months later. Two more things delay the effect of baits: "Female cockroaches with egg cases do very little feeding and avoid open spaces, so they are less likely to be immediately affected by a bait" (UC IPM), and German nymphs often hatch while their mother is still carrying the case in a hiding place.

Use the incubation times above as your watch period. At 24 °C (75.2 °F), young nymphs from cases already laid can keep appearing for up to about 28 days for German cockroaches, 57 days for American and 83 days for brown-banded. A few small nymphs in that window is expected; new adults, or numbers that keep rising after it, mean breeding is continuing. The cockroach removal timeline planner uses these same hatch times to set a realistic, week-by-week plan.

How this hatch timer works

Both modes use the shared cockroach data model on this site, so the incubation times here are exactly the egg-case figures on the life cycle and species pages.

• Incubation: straight-line interpolation between measured temperatures, held at the nearest measured value outside them (the result says so): German 28 days at 24.4 °C and 14 at 35 °C; American 57.4 at 24.4 °C and 31.8 at 30 °C; Oriental 81 at 21 °C and 42 at 29.5 °C; brown-banded 95.6 at 22.5 °C and 49 at 28 °C; Florida woods about 48 at 30–36 °C.
• Hatch window: you rarely know a case's age, so for a loose case the window runs from the day you found it to the full incubation — except a loose German case, which hatches within about two days. For a case still on the female, the window ends at the full incubation and starts at the incubation minus the longest published carrying time (it is fresh).
• Nymphs expected: the published average hatch and eggs per case for that species.
• First adults: the hatch window plus the species' nymph development at your temperature (same model as the life cycle pages).
• Gestation explainer: forming, carrying and incubation for egg-laying species; internal pregnancy for dubia and hissing cockroaches.

Smokybrown cockroaches aren't timed, because no incubation figure we could verify was available. Egg cases kept cool hatch later, and not every egg hatches.

Frequently asked questions

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.