Cockroaches are one of the world’s most common pest species, invading homes and businesses throughout the world. A roach infestation can cause significant problems for people living in close contact with them, as they spread harmful bacteria around the home. Cockroaches have filthy habits and spend much of their time hanging out in sewers and drains. As a result, their bodies are covered in pathogenic bacteria and parasites which can easily contaminate food sources and preparation areas. These dirty critters are also responsible for spreading allergens, such as skin cases and fecal matter. This can aggravate or even cause allergic responses such as asthma attacks in individuals who have prolonged exposure to them.
As if all this wasn’t bad enough, roaches can also create a nasty stink in your home. Cockroaches emit an unpleasant, musty odor that becomes stronger and stronger as their numbers increase. If you have a significant infestation of these bugs, the smell can quickly become overpowering!
The two most common species of roach are the German Cockroach and American Cockroach. These critters can be found all over the world and are the biggest culprits when it comes to a home invasion. Understanding the life cycle of roaches can help when it comes to extermination, as knowing their habits and breeding patterns can give you an idea of the scale of the problem. So, what is the lifecycle of cockroaches? Read on to find out about the lifespan of various roach species, how these insects develop from egg to adult and their breeding habits and behaviors.
Common cockroach terminology
Ootheca: The protective case surrounding a cluster of roach eggs. Each ootheca can contain up to 40 eggs, depending on the species of cockroach.
Nymph: A baby cockroach.
Molt: The process of shedding skin. Each cockroach will molt several times as it matures.
Instar: The name given to the nymphal stages between molts.
Cockroaches are simple creatures and have only three key life stages. These are:
- The egg stage: The roaches hatch from eggs laid by the female. These are contained within a protective casing known as the ootheca, which is deposited in a safe location by the female before hatching.
- The nymphal stage: Young cockroaches are known as nymphs. As they mature, nymphs will molt several times, shedding their skin each time they do so. Although roaches undergo some degree of metamorphosis during this time (e.g. by developing wings) they mostly just grow bigger over the course of their development.
- The adult stage: Once roaches reach full adult size they are able to breed and produce offspring of their own. Unlike nymphs, most adult roaches have wings, although they rarely use them.
German cockroach life cycle
The German Cockroach has three distinct life stages; the egg, the nymph, and the adult.
Cockroaches lay multiple eggs at once, which are contained in a protective sack known as an ootheca. In the case of German roaches, these egg sacks are bean-shaped and light, yellowish brown in color. They have a ridged appearance and are 7 – 9 mm in length.
German roaches are prolific breeders and can produce one egg case every 6 weeks under favorable conditions. These typically contain around 40 eggs, and the baby roaches will emerge after just 28 days. Female German roaches will carry their egg capsules on their abdomen until they are almost ready to hatch, depositing them just a few hours before the babies emerge.
Baby cockroaches are known as nymphs. These emerge from the cockroach egg sacks as tiny insects around the size of a period or full-stop. They are dark brown in color with a distinctive light brown or tan patch on their backs. German baby cockroaches change shape as they mature going from round to teardrop-shaped, to cigar-shaped when they reach adulthood.
German cockroaches go through, on average, six nymphal stages (or instars) before they reach adulthood. During this time, they will shed their skin (or molt) six times over a period of several weeks. Young cockroaches are white in color immediately after they molt, darkening to brown within a few hours of shedding their skins. Although males and females undergo the same number of molts, male German cockroaches will emerge as adults more quickly than the females, taking around 35 days to reach full maturity.
Adult German Cockroaches are typically 10 – 15 mm long. They are light brown in color and have two distinct parallel bands running from their heads to their wingtips. Once they reach adulthood, German Cockroaches breed immediately and continuously and can produce offspring throughout the year. As a result, there are usually several generations of German roaches living alongside one another in a single colony.
On average, male German cockroaches live for 100 – 150 days. Females survive much longer, with an average lifespan of 190 – 200 days. Unlike baby cockroaches, adult specimens have wings, though they rarely use them. They are highly adapted to running and can move very quickly on both horizontal and vertical surfaces.
German roach lifespan
- Egg stage: German Cockroach eggs incubate for 28 days before they hatch.
- Nymphal stage: The nymphal stage of the German roach is shorter for males than for females. Males will reach adulthood after 35 days under favorable conditions, whereas females will take around 60 days to fully mature.
- Adult stage: The total lifespan of the male German Cockroach is 100 – 150 days. Females survive much longer and will live for 190 – 200 days in total.
American cockroach life cycle
Like the German Cockroach, the American roach has three distinct life stages. These are the egg stage, the nymphal stage, and the adult stage.
An adult female American Cockroach will produce an egg case around one week after mating. This egg sack (or ootheca) is reddish or dark brown in color when it is first deposited but turns black after a day or two. They are purse-shaped and smooth in appearance. These sacks are usually around 8 mm long, roughly the same size as those of German roaches.
Unlike German Cockroaches, however, female American roaches deposit their egg sacks shortly after they are formed. The egg sacks are carried for just a few hours or a few days before being left somewhere safe to incubate. American roaches use a saliva-like oral secretion to glue the capsule securely to the ground.
American cockroaches leave their egg cases in protected areas, such as in cracks or crevices. They can often be found near food sources, as the baby roaches will have to forage for sustenance as soon as they emerge from the egg. Each ootheca typically contains 14 – 16 eggs, which will hatch after 29 – 58 days depending on surrounding conditions.
Young cockroaches are known as nymphs. In the case of American roaches, the babies look a lot like smaller versions of the adults except they are grayish-brown in color. As they grow they will gradually darken in color, becoming reddish-brown in the later nymphal stages.
Maturation of American Cockroach nymphs is heavily influenced by their surrounding temperature but usually takes around 600 days on average. During this time, the nymphs will molt 10 – 13 times before they reach adulthood, casting off their skin cases each time. The young roaches will be white in color immediately after each molt, darkening to grayish or reddish brown within a few hours.
During their development, American roaches will become progressively larger until they reach their full adult size. They will develop wing pads during their second to last instar, however, only the adults have wings.
American Cockroaches reach adulthood after 10 – 13 instars (nymphal stages). At full maturity, they are 1.5 – 2 inches long and reddish brown in color, with a pale yellowish band around the outside of the abdomen.
Not only are American roaches much bigger than their German cousins; they also survive much longer. It takes an average of 600 days for an American roach to reach adulthood, and the adult lifespan may be a further 400 days under favorable conditions. This is remarkably long for an insect and is thought to be largely due to their ability to resist pathogens and pesticides.
During the course of her adulthood, female American roaches will produce an average of 150 young. And although adult American roaches have wings (unlike the nymphs), they rarely fly. Instead, they are often seen running at speed over horizontal and vertical surfaces alike.
American roach lifespan
- Egg stage: American cockroach eggs will usually incubate for 29 – 58 days before they hatch.
- Nymphal stage: The nymphal stage of the American Cockroach varies significantly depending on the surrounding temperature and can take anywhere from 160 – 900 days. The average developmental period, however, is around 600 days under ordinary room conditions (70F/20C).
- Adult stage: The adult lifespan of the American Cockroach is also heavily influenced by the external temperature. At 70F/20C (i.e. ‘normal’ room conditions), adult roaches can survive for up to 400 days.
How big is a baby cockroach?
Baby cockroach size varies from species to species. Immediately after hatching, American baby cockroaches look much like adults in terms of their shape, but they are much smaller in size.
German baby cockroaches are tiny when they first emerge from the egg. The first instar is only the size of a period or full stop and they are round in shape. As they grow they will get bigger and change shape, gradually becoming teardrop then cigar-shaped.
How big can cockroaches get?
The size of the adult cockroach varies from species to species. German Cockroaches are around 0.5 inches long when they reach their full size. American Cockroaches, on the other hand, are much bigger and will grow until they are 1.5 – 2 inches long.
How long do roaches live for?
The cockroach lifespan varies depending on what species you are dealing with. German Cockroaches will live, on average, for 100 – 200 days. American cockroaches, however, can survive for a whopping 700 days! This is extremely long for an insect and is thought to be due to the American roaches ability to resist pathogens and pesticides. They are also skilled at avoiding toxins and can even regenerate lost limbs!
How many offspring can a cockroach produce?
German Cockroaches are prolific breeders and are sexually active as soon as they reach adulthood. Each female German roach will produce 4 – 6 oothecae over the course of her lifespan, each yielding up to 40 babies. Female American Cockroaches, on the other hand, produce, on average, 9 – 10 ootheca over the course of their lives. Each sack contains 14 – 16 eggs, yielding approximately 150 baby roaches in total.
Understanding the life cycle of cockroaches can be instrumental in effectively removing them from your home. The presence of roach eggs can be a strong indication of how large the population is and finding a large number of eggs around your property is a sure sign of infestation. So once you have an idea of the scale of the problem, you can take the appropriate steps to eradicate your roaches. This can be done using methods that are easy to implement at home or if your cockroach situation is out of control, a professional exterminator can take care of things for you.