Cockroaches breed fast, with some species reproducing more rapidly than others. The fastest-reproducing domestic cockroach is the German cockroach, which can produce an egg case with 48 eggs every six weeks, potentially leading to the generation of over 100,000 further roaches over a year.
Temperature affects the cockroach lifecycle, with colder temperatures slowing down maturation and reproduction, and warmer temperatures supporting faster and more effective reproduction.
There are over 4000 species of cockroach out in the world, belonging to six different taxonomic families.
If you’re interested in learning more about how often cockroaches reproduce, then keep on reading for all the fun facts about common cockroaches including:
- how many eggs cockroaches lay,
- how long it takes for cockroach eggs to hatch,
- how fast cockroach nymphs mature,
- factors that influence the speed and pattern of cockroach reproduction,
- the average lifespan of cockroaches.
How many eggs do cockroaches lay?
When you’re thinking through the speed and timing of cockroach reproduction, the first important factor to consider is the number of eggs each female roach lays at any one time.
Cockroaches are prolific breeders and their populations can grow exponentially.
While the total number of eggs laid by a cockroach female depends very much on the individual species of roach, in rough general terms, a female can produce approximately 6-14 egg capsules during a lifetime.
Each ootheca (scientific term for egg capsule) contains around 16 individual eggs, which means that female cockroaches can each produce an average total of around 128 eggs.
The four most common indoor cockroach species found in the USA are are German, American, Oriental and brown-banded cockroaches. Each of these species displays its own pattern and level of egg production.
The German cockroach
Also known as water-bugs or palmetto bugs, German cockroach females can produce many more eggs than the rough average.
They lay an egg case approximately every six weeks, with each ootheca containing around 48 eggs. A female might therefore be responsible for propagating successive generations amounting to well over 100,000 offspring in a single year!
The American cockroach
American cockroaches can produce two oothecae of 16 eggs each week at the peak of their fertility but this then falls to one ootheca per month. An American cockroach might generate 800+ new roaches per year.
The Oriental cockroach
Oriental cockroach females produce around eight oothecae with an average total of 200 eggs during their lifetimes
The brown-banded cockroach
Brown-banded cockroach females produce about 12 oothecae of 16 eggs in the course of their lives.
How long do cockroach eggs take to hatch?
Another critical factor in determining how often cockroaches reproduce, is the speed at which eggs develop and hatch. On average, cockroach eggs may take roughly 4-8 weeks to hatch but again there is variation between species.
German cockroaches hatch after around four weeks. Brown-banded roach eggs hatch after around 6-7 weeks. American and Oriental cockroaches both hatch in approximately eight weeks.
When are cockroaches mature enough to reproduce?
Speed of maturation is also an important consideration, with different species maturing at slightly different rates. Reaching adulthood could take anywhere from a few weeks in some species to 1-2 years in others.
German cockroaches are a fast maturing species with the females able to lay eggs after only a few weeks of life. German cockroach females also carry their eggs right up until hatching, boosting the survival chances of their offspring.
Brown-banded cockroaches reach adulthood more slowly than German cockroaches, taking around 2.5 – 4 months to achieve full maturity. Similarly, American cockroach females are able to breed after about 15 weeks.
Oriental cockroaches are even slower to mature, potentially taking 6-12 months before they are able to reproduce.
How do cockroaches reproduce?
The overall pattern of cockroach reproduction is similar to reproduction in many other insects, and does not vary greatly between roach species.
The process begins when female roaches emit pheromones to attract males for mating. The males may fight one another for the right to approach females, demonstrating their strength and fitness.
When the female cockroach finds a mate, the male deposits his sperm into the female and fertilizes her eggs.
The majority of cockroach species are oviparous, meaning that offspring grow in eggs deposited outside the mother’s body. The fertilized eggs first develop in an egg capsule called an ootheca, attached to the mother’s abdomen, until she is ready to lay them.
Cockroach females deposit their egg cases in secluded sites, and some species glue them onto surfaces using their saliva or other fluids. Most cockroach species carry their oothecae for less than two days.
German cockroach females carry their eggs with them for longer, perhaps 15 days or more, and then lay the eggs when they’re almost ready for hatching.
American cockroaches carry fertilized eggs for only a few days and then deposit them in a safe, warm, damp environment, perhaps a corner near a food source.
Some roach species are ovoviviparous, meaning that offspring develop in an ootheca within the body of the mother and hatch alive from that.
One species is viviparous, with eggs developing inside the female roach’s uterus without any ootheca, and hatching directly from their mother.
The level of care given by cockroach mothers to offspring also varies. In some species, females hide or bury their eggs and then completely abandon them, while others will provide some level of care after hatching.
Newly hatched cockroaches are known as nymphs. They usually begin white, turning brown in a short time as their exoskeletons harden and they begin to resemble a smaller, wingless version of adult cockroaches.
These nymphs molt as they grow and develop towards adulthood, with each molting giving them a more adult form and size.
Cockroach mating season is largely in the summer months since this provides the warm, moist atmosphere their eggs need to survive and develop. During colder winter months, cockroach reproduction slows significantly.
Can a female cockroach really reproduce without a male?
Female cockroaches can sometimes produce and lay eggs without a mate! This asexual reproduction process is called pathogenesis and is also found in other insect and wider arthropod species. It normally only occurs when there are no available males.
In the absence of males, virgin female cockroaches who live with other females produce offspring more quickly than virgin females who live alone.
Parthogenesis means that female cockroaches can continue to reproduce for years without needing to mate, but will only produce all-female descendants. (As offspring develop solely from the mother’s egg cells there are no Y chromosomes available to create males.)
While asexually produced offspring are capable of mating and continuing the cockroach lifecycle, hatchlings resulting from parthogenesis will lack genetic diversity and may be less likely to survive to adulthood.
Do female cockroaches lay their eggs when squashed?
It is largely a myth that female roaches lay eggs automatically when dying.
Unless the eggs were fully developed and on the point of hatching when the mother dies, the chances are that whatever killed the pregnant female (poison, a shoe, predators etc…) will also kill the eggs.
Eggs which have not developed to the point of viability will cease to develop with the death of the mother.
If you do find more adult roaches appearing after you kill a cockroach, this may be because dead cockroaches emit oleic acid secretions which are interpreted as food signals by other roaches.
Ensure that you dispose of dead roaches properly after killing them to ensure that your home doesn’t become infested.
What is the lifespan of a cockroach?
Again, this varies according to species with some living only a few months and others having lifespans of 2-3 years or more in optimal conditions.
American Cockroaches are amongst the longer-living roaches with lifespans of more than a year. The average German cockroach lifespan is about 100 days, although females can live for more than 200 days.
Oriental Cockroaches might live for another six to 12 months after reaching maturity. Once adult, brown-banded cockroaches can live for a further 60-80 days.
What wider factors affect how often cockroaches reproduce?
While cockroaches have a mating season and general pattern of reproduction this is not governed by an exact schedule and can be affected by a number of external factors.
Temperature and touch, for example, are both critical in influencing how fast and how often cockroaches produce young, and how fast these offspring mature.
Warmer temperatures stimulate cockroach reproduction and growth. Adults are more active and eggs and nymphs have better chances of survival in warm, damp conditions.
Female cockroaches also produce eggs faster when they are touched by other cockroaches, or by similar artificial means, than when they are alone.
It appears that this kind of touch can stimulate the production of certain hormones that speed up female roach reproduction.
A final word…
Cockroaches are a fast breeding type of insect and one or two females can generate a whole domestic infestation in a very short space of time.
The potentially exponential growth of cockroach populations means that it’s important to exterminate roaches when they first appear if you don’t want them to take over a whole home or apartment block.
Alright, that’s it for this article, here are a few hand-selected articles that you might also find interesting reads:How Much Do Cockroaches Eat?
11 Tips to Prevent American Cockroaches
15 Unusual Facts about Cockroaches that will Keep you up at Night
Finding tiny black bugs in your bathroom can be uncomfortable, to say the least. Especially if they are persistent, or they appear in very large numbers, which they often like to do. When it...
A short horror story: You get a new houseplant. You do your best to take care of it. You’ve ensured that it has the right soil, the right amount of sun, it gets enough water. And then one day, you...