cockroach shedding exoskeleton

Do Cockroaches Shed Skin? 3 Shedding Exoskeleton Stages

If you’ve found the shed skin of cockroaches around your home, this can be an indicator of a cockroach infestation. Roach exoskeletons are usually found in cockroach nests. However, it’s not entirely impossible to find some in basements, cabinets, and bedroom corners. By noting the shed skins they leave behind, you can better learn how to exterminate them.

Cockroaches shed their skin through a process called molting. They are protected by a tough exterior shell called an exoskeleton (or exuviae). Cockroaches aren’t able to grow past the limits of their hard exoskeleton. Because of this, they have to shed that rigid skin in order to grow bigger. Depending on the species, cockroaches molt 11 to 13 times to grow from nymphs (baby cockroaches) to adults.

Once they finish molting, roaches shed their old skin and leave it behind. A single cockroach shell can tell you where a nest is located or how many cockroaches are there. It can also indicate how soon you can expect a new wave of cockroaches to be born.

Why Do Cockroaches Shed Their Skin?

We first have to understand what kind of insect they are. Cockroaches are invertebrates, which are animals that do not have a spine. More specifically, cockroaches are arthropods, a type of invertebrate defined by their:

  • Soft, segmented bodies
  • Exoskeleton
  • Legs with multiple joints

Unlike vertebrates, invertebrates don’t have a skeletal system on the inside of their body. Instead, their skeletal system is on the outside in the form of an exoskeleton. It’s also known as the outer skin or shell. This shell does the following:

Gives Roaches Structure

The exoskeleton is what holds cockroaches together. It serves as the framework that keeps the body in place. It allows the cockroach to move its muscles and control each segmented part properly. Without the exoskeleton, a cockroach’s mushy body would fall apart. It’s no different from how a human would fall apart without a rigid interior skeleton.

Gives Roaches Strength

Exoskeletons are stiff and tough enough to protect cockroaches from all kinds of harm. This includes getting stepped on or smashed with a book. However, because the outer shell is so rigid, cockroaches have to shed their skin in order to grow.

Allows The Roach To Grow

When a cockroach is born, its skin is soft and white. The exoskeleton will then harden and turn brown after a few hours. To achieve maturity and grow into a full-sized adult, cockroaches must go through a molting cycle. Here, they periodically:

  • Shed their exoskeleton
  • Grow
  • Then harden their new skin

Not all insects mature this way. Cockroaches do because they have an incomplete metamorphosis, as opposed to a complete one.

cockroach malting stages

Lets Roaches Complete Their Metamorphosis

An insect with a complete metamorphosis is born as a larva, the juvenile phase of some insect species. Complete metamorphosis consists of the insect going through a very abrupt physiological change in order to mature into an adult. It’s like a worm enveloping itself in a cocoon and coming out as a butterfly. In the case of insects with complete metamorphosis, the juvenile insect looks nothing like its adult form.

Cockroaches, on the other hand, have a molting cycle because of their incomplete metamorphosis. The juvenile cockroach (nymph) hatches and looks nearly identical to an adult roach save for:

  • Their smaller size
  • The lack of wings (depending on the species)
  • Underdeveloped genitals.

They eat and behave in the same way their parents do and have the same daily activities. Their growth process is gradual and is only complete after a series of molts.

Cockroach Molting Stages

Like any living organism, the developmental stage is the most important part of a cockroach’s life. It’s what determines how big a cockroach will grow, as well as its survival chances. Things which affect the roach’s molting cycle include:

  • Amount of food it has
  • Availability of shelter
  • Amount of water it has
  • Stress levels

When dealing with an infestation, you can use this to your advantage. With the right timing, you can leverage the cycle to bring about a colony’s downfall.

Development of the First Exoskeleton

When a cockroach hatches, it is soft and white in color. It’s very uncommon to see newly-molted white cockroaches. That’s led to the belief that white cockroaches are a rare species of albino insects.

In truth, newly-molted cockroaches are so rare to see because they are at their most vulnerable right after shedding their skin. They stay well hidden.

Nymphs expand a bit by taking in oxygen and filling themselves with air. In the next few hours after molting, the exoskeleton hardens and turns brown.

First Molts

After the nymph has developed its first exoskeleton, the molting process begins a few days to weeks later. Remember, the exoskeleton is what holds the cockroach’s body together. As such, it’s impossible for the cockroach to break out of its shell without first developing the new skin.

Right underneath the old exoskeleton, the cockroach forms a thin, soft cuticle. This will help it retain moisture. It will also control its muscles once it’s ready to break through the old shell.

The cockroach then proceeds to escape from its shell. It is a difficult and arduous process. Not all cockroaches manage to survive it.

Because the new exoskeleton was formed underneath the old one, it is slightly smaller. In the same way they did immediately after hatching, the nymphs take in air to expand their muscles. They do this every single time they molt, until they grow to full size and reach adulthood.

Cockroach exoskeletons are shaped like cockroaches and are light brown in color. If left alone, the exoskeleton will eventually become brittle and easy to disintegrate. When small bits of cockroach skin break up and are scattered by the wind, it can spread disease. It may also trigger allergies if touched or inhaled.

Failing The First Molts

Without a proper exoskeleton, some cockroaches lack the strength to get out of their old shell. They may also injure themselves while trying. Many nymphs are eaten by hungry, cannibalistic adult roaches while in the process of shedding.

This is why, before beginning the molt, cockroaches hide themselves away in humid, secure spaces. Here, they can be safe while in their weakened state. With their white, unhardened exoskeleton, they are at risk of dehydration and bacteria when exposed to the air. They are also unable to move much, so they need to stay still until the new skin hardens.

Final Molt

It is only during the final molt that cockroaches emerge with their wings and fully developed reproductive organs. Depending on the species, a cockroach will have molted 5 to 14 times over the span of 1 to 6 months.

Science Behind A Cockroach Shedding Exoskeleton

According to the Proceedings of the National Academy of Sciences, there are at least 6 different hormones that regulate molting.

The first one is 20-hydroxyecdysone, a steroid hormone present in most arthropods. It’s the protein that is in charge of forming the new exoskeleton underneath the old one. In cockroaches, this protein is secreted by the fat bodies.

The 20-hydroxyecdysone is a hydrophobic hormone, with hydrophobic literally meaning “fear of water”. Hydrophobic hormones do not flow through the bloodstream. Instead, they travel around the fat bodies and permeate through to the cockroach’s tissues.

In order for the cockroach to have a successful molting cycle, it must have a balanced amount of 20-hydroxyecdysone. If the roach doesn’t manage to secrete enough of the hormone, the cockroach cannot form the new skin. Should the cockroach have an overabundance of 20-hydroxyecdysone, the results could end up costing the cockroach its life.

Hormone Imbalance During Molting

That’s because 20-hydroxyecdysone is a phytoecdysteroid. Phytoecdysteroids are chemicals that plants produce to protect themselves from being eaten by insects. When a cockroach consumes plants that contain phytoecdysteroids, it overrides the molting process. This causes the cockroach to:

  • Molt prematurely
  • Lose weight
  • Disrupt its digestive process
  • Die

Researchers have a theory on how cockroaches developed the ability to secrete 20-hydroxyecdysone and perfect their molting process. It’s due to eating plants that produce them. Although phytoecdysteroids are toxic to insects, cockroaches are rarely deterred by the toxicity in the things they consume. That’s thanks to years of evolution.

Cockroaches can become immune to certain insecticides in the span of a single generation. As such, researchers theorize that after millions of years of consuming phytoecdysteroid-producing plants, cockroaches evolved to regulate the amount. With control over how it affects them, they can leverage its perks.

Other Molting Hormones

The next 4 hormones involved in cockroach exoskeleton shedding are a series of peptide hormones. These are a chain of amino acids that regulate certain biological functions, such as:

  • Stress levels
  • Growth
  • Immunity

Peptide hormones are located in a roach’s gut. They work to make sure the cockroach has enough strength to shed its exoskeleton. They also help the pest maintain a healthy weight through the whole process.

The final hormone in the sequence shows up later in the molting game: bursicon. Bursicon is released after the cockroach has shed its exoskeleton. It triggers the start of the tanning and hardening process in the new skin.

Can Roaches Shed Their Skin To Regenerate?

Cockroaches are able to regenerate their limbs by molting. However, limb regeneration can cause quite a disturbance in the molting cycle of a nymph.

When a cockroach loses its leg, a delay in the next molting cycle occurs. This is so the roach can prepare its body to heal. Once this period of healing is complete, the cockroach can begin the shedding process.

According to the University of Massachusetts, the delay in the molt is not determined by the damage done to the injured roach. Instead, it’s decided by a biological clock that ensures that the molting cycle of a single nymph is synchronized with its brothers and sisters.

The length of the delay can be extended significantly if the limbs are removed one after the next. The last cockroach limb to be removed is the one that resets the next cycle. For example, imagine a cockroach loses a second limb before it can molt and regenerate a new one. The cockroach will then not molt until the second wound goes through the healing period.

This greatly endangers cockroaches. It not only leaves them vulnerable to predators due to a lack of limbs. It also delays the molt, forcing the roach to wait to grow bigger and stronger.

Can Cockroaches Shed Their Wings?

Cockroaches are not capable of shedding their wings. Likewise, they cannot regrow them. Cockroaches only develop their wings during the final molt. Once the cockroach has reached full adulthood, it is incapable of gaining its wings back.

If you find light brown wings somewhere in your home, it’s very easy to think that a cockroach has shed its wings in that spot. However, if the wings were all you found there, it’s very likely that those aren’t cockroach wings at all. Cockroaches are not capable of tearing off their own wings. As such, the only way for them to lose them is by getting attacked by another creature.

Whether it’s battling with a cat, dog, human, bird, or other cockroaches, it’s pretty common for the fighting ring between a cockroach and predator to be messy. Aside from losing wings, during a fight, the roach also:

  • Spills blood
  • Defecates
  • Loses limbs
  • Loses antennas
  • Loses parts of its broken exoskeleton

If you see cockroach wings without any other sign of roaches, they may in fact not be cockroach wings. Termites are insects that are very much like cockroaches, including the color of their wings. Queen termites rip their own wings off before starting a new colony. So, make sure to check for a termite infestation as well as a cockroach one if you are finding light brown wings around your house.

Do Roaches Eat Wings And Shed Skin?

Cockroaches will often eat their own shed skin because of the nutrients it contains. This depends on how long the wings have been there and how many hungry cockroaches are residing in your home. It would be odd for a cockroach not to have eaten the wings and skin.

What Is a Cockroach Exoskeleton Made Of?

Cockroach exoskeletons are mostly made of a protein called chitin. Chitin is a fibrous material that is comparable to keratin in mammals. It’s the reason why cockroaches have such hard shells.

To put it into perspective, hooves, horns, claws, and fish scales are made of keratin. Chitin makes exoskeletons so tough that cockroaches are able to withstand 300 to 900 times their own body weight.

Besides chitin, which is made of nitrogen, exoskeletons are also composed of other composite materials, such as sclerotin. When scientists deacetylate chitin, they remove the admixtures and turn pure chitin into a concentrated substance. Through this, we are able to see just how much chitin is located in each part of a cockroach’s body.

Cockroach Body PartPercentage of Chitin
Dorsal Abdomen37.65%
Hindwings18.22%
Ventral Abdomen37.24%
Metathoracic Legs35.55%
Mesothoracic Legs33.28%
Prothoracic Legs32.24%
Pronotum31.55%
Head31.07%
Genitalia29.28%
Dorsal Thorax29.07%
Ventral Thorax28.33%
Antenna27.77%
Cerci25.65%
Forewings19.99%

Cockroaches don’t have chitin in their alimentary tracts. That’s because this part of their body is on the inside and does not need to be hardened. What really boggled scientists, however, was the lack of chitin in the oothecal.

These are the sacs mother roaches keep their eggs in. Despite having the same coloring as exoskeletons and their hard exterior, no traces of chitin were found in the ootheca of any cockroach species.

What Does It Mean When You Find a Cockroach Exoskeleton?

Finding cockroach exoskeletons around the house is worrisome. It can give you a lot of information about the state of the infestation in your home.

Safe Spots

When cockroaches are molting, they are extremely vulnerable. They are at risk of dehydration when they break out of their shell and are unable to move properly. That’s why they prefer to molt in damp crevices where they won’t be bothered.

Finding a cockroach exoskeleton means that the roach had nowhere safe to molt and all possible crevices were overrun with other cockroaches.

Cockroaches are soft and defenseless a few hours after shedding their skin. It’s very common for hungry adult roaches to eat nymphs. A roach that had to molt out in the open is one that had to make two very difficult choices in order to survive.

why do cockroaches shed their skin?

Lacking Resources

On the plus side, this could mean that the cockroaches inhabiting your house are lacking in resources. This makes them much easier to exterminate. When cockroaches have an abundance of food, they don’t feel the need to eat other cockroaches.

As a matter of fact, cockroaches avoid other dead roaches. Their corpses exude a nasty odor that alerts insects where a death has occurred. Only starving cockroaches turn cannibalistic.

This can work in your favor when using roach bait. A roach that eats roach bait and dies is then eaten by hungry roaches. These can then return to the colony and spread the poison through their contaminated feces. Other cockroaches may consume this and die off.

New Hatches

Cockroach exoskeletons also tell you how soon you can expect a new wave of roaches to hatch. If there are molting cockroaches in your home, you can expect the insects to start procreating in the span of a few weeks. This depends on the size of the exoskeleton and how far along into the nymph stage they are.

The nymph stage is the best time to try to exterminate roaches or disrupt their molting cycle. After all, this is when the expansion rate of their population isn’t at its peak.

How to Disrupt Cockroach Molting Cycles

There are many insecticides that act as growth regulators. These substances sabotage the hormonal balance in cockroaches, causing:

  • Sterility
  • Premature molting
  • Death

Adult roaches affected by insect growth regulators may still live. However, any eggs they produce never hatch or the adult remains sterile for the rest of its life.

Juvenile roaches affected by insect growth regulators are unable to finish their molting cycles. This causes them to stay as nymphs and have a short lifespan, or to die while in the process of molting.

Using insect growth regulators is a much slower way of getting rid of a cockroach infestation than traditional methods. Cockroaches die 3 to 10 days after being affected by IGRs. It is, however, safer to use than normal insecticide; they are not neurotoxins, which attack the nervous system.

Putting Anti-Roach Chemicals On Plants

As mentioned, an excess level of 20-hydroxyecdysone can cause the cockroach to die. Hormonal imbalance is one of the many ways you can exterminate the cockroaches currently in your home. It can also prevent further procreation among them.

Remember, 20-hydroxyecdysone is a phytoecdysteroid. That is a type of chemical produced by plants that causes a hormone imbalance when cockroaches eat them. You can place plants and vines that produce phytoecdysteroids both inside and outside your house. They will serve as natural cockroach growth regulators. The plants that produce phytoecdysteroids are:

  • Achyranthes bidentata Blume (ox knee)
  • Tinospora cordifolia (gurjo, giloy, guduchi, heart-leaved moonseed)
  • Hebanthe eriantha (Brazilian ginseng)
  • Rhaponticum (maral root)
  • Serratula (Plumeless saw-wort)
  • Asparagus

With the use of these, you can use a roach’s skin shedding to put a serious dent in the colony.