Similar to other insects, the cockroach life cycle starts when a female cockroach lays eggs. There is no specific number of eggs that a female can lay because it varies in different species. Regardless if there are American cockroach, German cockroach or Oriental cockroach in your property, there are three stages that they all go through till they transform into an adult.
Life Stages of a Cockroach
The three life stages that a cockroach goes through are the following:
Approximately a week or two after mating, a female will start producing a casing. The casing, known as the ootheca, is the sack used by females for carrying and protecting her eggs. These egg cases are hard shells made out of the secretions from female glands.
They are purse- or kidney-shaped. The size and colour of the casings differ from every species.
One oothecal may contain 10 to 40 eggs, sometimes 50 cockroach eggs. Throughout a female’s life, she will be producing a lot of these casings. Once she deposits the eggs, she will start looking for a secure location to hide them.
Most of the time, these areas are warm and dark areas that are moist and near food sources. This makes the area a suitable environment for newly hatched nymphs.
Depending on the species as well as the living conditions, incubation period varies. Normally, it will take around 24 to 60 days until the eggs hatch. However, there are times when the incubation takes longer.
Once the eggs start hatching, immature cockroaches emerge. These are cockroach nymphs. The eggs will only hatch under ideal external conditions. Nymphs will only wait for till the temperature is right before they emerge.
Nymphs are usually white in colour as they emerge from their shells. Once the exoskeleton hardens, they will eventually turn brown. The process makes them look like small versions of the adult cockroaches. However, they don’t have wings.
This is the stage where they have to go through several instar stages. In every stage, they will moult. It is the process where they are shedding their skin several times.
They will become lighter in colour and they will have soft and fragile bodies again. Then, their bodies will reharden and the colour will darken.
As the nymph goes through several moulting processes, they will start to look more like adults. The time needed for every process still depends on each species. There are species where nymphs can moult 5 to 15 times and may take a few weeks to several months to complete.
Once the final moult happens, nymphs will become adult roaches. They have developed wings and their reproductive systems are already fully functional.
With ideal conditions and sufficient food supply, adult females can start producing eggs that increase their population quickly. Under cold temperatures, the entire development process may take more time and will be slower.
How Do They Reproduce?
Females usually attract males to fertilize eggs. For this to happen, she will be releasing pheromones that will attract males. This may result in males competing and fighting each other to mate with the female.
Most of the time, females will only mate once and then store the rest of the sperm to continue producing eggs after. Others may have to mate as often as possible, as the sperms may deplete in time.
Reproduction methods differ in every species after the mating process. In every species, females will produce eggs in three different methods.