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 tho