Cockroach Larvae: Complete Lifecycle Process Explained

Cockroaches are pests found on every continent on Earth except one, which is Antarctica.

Cockroach infestations can appear in warehouses, hospitals, offices, restaurants, and several other areas where food handling takes place. Cockroaches can leave behind stains on the surface and a bad odor due to the substance they secrete.

Cockroaches belong to the order of Blattodea, which also includes termites. There are thousands of species of cockroaches existing all over the world. Of these, about 30 cockroach species are generally seen inside houses.

Some of the more popular cockroach species are the German cockroach, American cockroach, Oriental cockroach, brown-banded cockroach, Surinam cockroach, Madeira cockroach, Australian cockroach, and Pennsylvania wood cockroach.

The bodies of the cockroaches are flattened and oval-shaped. The roaches also have long antennae around their body length. When viewed from above, the cockroach appears to have no head. This is because the head is hidden from view.

Cockroaches also have six legs, three on each side. The legs of the roaches are covered with spines. Although many adult cockroaches develop wings, only a few use them to fly.

Meanwhile, the young and immature cockroaches are similar to the adult cockroaches in appearance only with the exception of wings. Their bodies are also slightly smaller than the adult ones.

The Life Cycle Of A Cockroach

On average, a cockroach lives for about 20-30 weeks. This might seem to be a very short period and does not explain the large number of these pests lurking around. Their population keeps on increasing despite their short lifespan because of their reproduction process.

The life cycle of the cockroach involves three stages: egg, nymph, and adult. These stages are the same for every species of cockroach.

The egg stage is the first stage for roaches. The female roach does not lay one single egg at a time. There are several eggs encased in an egg case called an ootheca.

The oothecae are dark brown or black in color and have a shape that looks like a kidney bean or a purse. The oothecae act as a shield for the eggs contained inside. They protect the eggs from insecticide and predators.

The oothecae are made up of a leathery material. Each ootheca consists of about 16-50 eggs.

The exact number of eggs in an ootheca depends on which species of cockroaches it belongs to. While the smoky brown cockroach is known to produce around 20 eggs in a single ootheca, the German cockroach can produce around 30-48 eggs at a time.

The oothecae of the Smoky brown or Oriental cockroach are slightly bigger in length than those of the American or German cockroach. The smallest ootheca is that of the brown-banded cockroaches.

The ootheca has a small ridge that runs along its entire length. This ridge is called the keel, which is considered a weak spot used by the nymphs to come out of the egg case. The eggs are double-lined inside the ootheca, and they hatch inside. The larvae of cockroaches are known as nymphs.

The larvae, or nymphs, breathe in air to make themselves bigger. As their size increases, the keel opens up to let the nymphs out. It closes back up when all the nymphs have left.

Each nymph then undergoes several stages involving the molting of their skin. This shedding of skin aids in the growth and development of the nymph.

According to the studies conducted on the topic, scientists have found that the nymph goes through a total of six molts before it becomes an adult. This process is estimated to take about 60-103 days to be completed.

The adult stage is the last stage of the life cycle of a cockroach. While as eggs, the cockroaches had the same features, they changed during the nymph stage, and as they became adults, females and males developed certain specific physical features to make them distinct from the other genders.

While the body of the male roach is slender with a tapered posterior abdomen, the female roach's body is stout with a rounded posterior abdomen. Cockroaches have six legs. There are three legs on each side. Roaches' legs have many spines. Even though all of them have wings, only some are known to use them to fly.

It is during the adult stage that the males work to attract the attention of the females. The main purpose of the cockroaches during this stage is to mate and reproduce more cockroaches.

What do baby cockroaches look like?

Many insects have larvae forms that look quite different from their adult forms. However, it is not the same for the cockroach species. The young cockroaches, known as nymphs, look like adults with only slight differences.

The young roaches are smaller than the adult roaches. They also do not possess any wings. The nymphs appear in black or dark brown, with clear bands running parallel to the pronotum length. The appearance of the nymphs might keep on changing as they go through the process of molting multiple times.

Scientists call the stage in between the molts an instar. The molting helps the nymphs develop into adults by increasing the size of their bodies. It also helps in the development of the different parts of the roaches' bodies, including the wings, which some of them use to fly.

The nymphs constantly forage for food and water in between molting—the food and water aid in their growth into adult cockroaches.

How often do cockroaches lay eggs?

The female cockroaches do not lay individual eggs but egg cases. The egg cases, collectively known as the oothecae, carry the actual eggs till they hatch to reveal the nymphs. The number of times the female cockroaches lay eggs in their lives depends on the species of cockroach.

The American cockroach can lay about 10 egg cases over its lifetime. The brown-banded cockroaches are known to lay around 13 egg cases in total. Meanwhile, the Oriental and the German cockroach can produce around eight oothecae in their lifetime. This is why female roaches generally have a longer lifespan than males, depending on the species of cockroach.

If the individual egg population was to be calculated, then the females could lay about 200-300 eggs in a year. This is why, even though the lifespan of the roaches is shorter, their population keeps on increasing.

How long can cockroach eggs lay dormant?

While some cockroaches try to find a specific location to lay their eggs, others carry the oothecae till the eggs hatch. The eggs do not hatch as soon as the ootheca is deposited or completely formed. It takes time for the hatching to take place and the larva to break out of the shell.

The incubation period for the cockroach eggs is about 24-38 days. If it takes longer than this, there is a chance that the larvae might never emerge from the ootheca at all.

In the process of incubation, the cockroaches place the ootheca in a secure and proper place. Some also use the sticky substance they can secrete to secure the egg case to a surface.

The American cockroach is known for sticking its egg cases on surfaces near food sources using its sticky saliva. The Oriental cockroach also lays the ootheca near food sources. However, these places are covered and warm. The smoky brown cockroach has a tendency to hide its oothecae inside humid crevices.

The ootheca of the brown-banded cockroach can be found on rough surfaces such as sand or cardboard. If the infestation rate of the insect is high, then the egg cases can be found attached in clusters.

Meanwhile, the German cockroach carries the ootheca extremely close to the cockroach eggs' hatching time. It is usually a day before the eggs hatch.

Sometimes, the eggs of the German roach might hatch while the ootheca is still attached to the body of the female. If the egg does not hatch, then the larva won't be able to come out. The eggs can only survive for a limited time period before they become useless.

Did You Know...

Many species of cockroaches are considered pests.

Cockroaches are sometimes confused with other insects such as crickets, ground beetles, leaf-footed bugs, and long-horned beetles.

Cockroaches carry several diseases that can result in diarrhea and food poisoning. The skin cast by the cockroaches and their saliva and feces can cause allergic reactions and asthma among humans, especially in children.

This insect can pollute the surface it walks on, which may often include food items, through dirt, germs, and bacteria stuck to its legs. Cockroaches can not only pollute the food in the house, but they can also damage products made from fabric and paper.

Along with the characteristic of carrying pathogens of diseases harmful to humans, this makes them a pest that can be very dangerous if their infestation isn't controlled.

Cockroaches are nocturnal insects, which means they are active during the night. The cockroach infestation is not visible during the day because they are hiding during this period. However, there are several other signs left behind by cockroaches, hinting at their infestation.

This pest is known to leave behind stains on the surface where they have crawled. Moreover, they also emit a bad odor that can be easily detected. The egg cases found near food sources, warm places, and crevices are also a sign of an infestation.

There are also various methods to determine whether there is a roach infestation in your house or not. You can use bait to lure the roaches out. The sticky baits must be placed close to the places that cockroaches usually prefer.

The traps should be put against the walls and meet the corners properly so that the roach does not have a chance to escape. As the roaches come out when it is dark, you might have to wait out the night and check the trap in the morning.

Once you have confirmed that there is indeed a roach infestation in your house, you need to then find the right treatment to get rid of them. Although there might be many home treatments and techniques to control the growth of this insect, it is highly advised to let professional pest control services take care of the infestation.

The pest control professionals would use a fumigation treatment to get rid of the roaches.

Furthermore, infestations of cockroaches can be prevented by keeping the places where the infestation can happen clean and hygienic.

Food items must be properly covered and kept in clean places. Regular cleaning of the place must be done. Moreover, stale food must be removed from the other edible items as it can attract roaches or other insects.

If you still see a sign of infestation after keeping the place clean and fresh, then there might be some other reasons for the cockroaches to roam around. In such a situation, the pest control professionals might need to conduct a thorough search of the neighboring houses and spaces too.

It is possible that there might be decaying matter you are not aware of that has attracted the roaches.

These scavengers can eat any edible entity they can find, which also includes rotting products. They are also known to eat hair sometimes. However, they have a preference for meat, starches, and sweets. Identifying what attracts the cockroaches can help to keep them away.