Do Bed Bugs Shed Their Skin? Do They Molt?

Bed bugs are a nightmare. They are incredibly difficult to deal with, and make you want to burn your house down. If you’re in the midst of an infestation, you may have found little husks around. Are those dead bed bugs, or do bed bugs shed their skin? Do they molt?

Similar to other insects with hard shells, bed bugs undergo molting. Yes, they shed their skin as they grow.

Here’s what we know about molting bed bugs.

  • Bed bugs molt as they transition from one phase of their lifecycle to another.
  • Molting does not occur in fully mature adults.
  • It is easy to mistake bed bug shells for living bugs.

We’ll explain it all below.

Do Bed Bugs Shed Their Skin?

Most bugs, not just bed bugs, shed their skin. The process is referred to as molting, a general term for old skin shedding, shells, or feathers to allow the growth of new ones commonly seen in insects. 

The process is critical; without it, a bed bug cannot complete its life cycle. This is the primary reason for the process – to complete the life cycle. 

Without molting, a bed bug cannot complete its life cycle.

Molting of a bed bug’s exoskeleton takes place since they outgrow their shells. Molting will occur between instar/life stages, and during each phase, they can double their sizes though the rigid shells do not grow as they grow. A new shell grows beneath the old one. Note that an adult bed bug will not molt since they do not increase in size. 

Since it is only non-adult bed bugs that molt, the bed bug shells you come across can indicate a growing or renewed bed bug infestation. If, for instance, you come across many bed bug casings under the mattress, you should immediately start heat treatment. 

Frequency Of Molting In Bed Bugs

Bed bugs shed their exoskeleton following a blood meal at each of the five nymph stages.

Provided that there is an abundant supply of food, (we’re talking blood here!) and optimum temperatures, every stage lasts for a week. Nonetheless, over cold temperatures and conditions of food scarcity, the bugs remain in their nymph stage for an extended duration. 

Upon reaching maturity, the bed bug stops shedding its exoskeleton. 

What It Means When Bed Bugs Molt

A bed bug will not shed its exoskeleton just for the sake of it. It does so because it needs to increase in size. It is also an indication of various factors. 

What Are The Signs Of Widespread Bed Bug Infestation?

Bed bug casings indicate that you have an infestation that has been quietly going on for some time. 

Infestations typically begin with solitary females. These females mate once and consequently lay eggs by the dozens, with the female’s hemocoel serving as sperm storage. The female bug will need a blood meal before laying eggs, and the eggs act as the initial infestation sign. 

The eggs take about two weeks to hatch.

After hatching, the nymph bugs begin to feed and shed their skin every time. The shed nymph casings are tiny and white, and thus you can easily miss them. This is because the size of nymphs is smaller compared to adults. Keep in mind that full-grown bed bugs are about the size of an apple seed, so a nymph is much smaller.

With continued feeding, the bed bugs become brown. 

In the earlier life stages, noticing the casings is a challenge. You will likely notice the instar shells, which are easier to spot later. Therefore, if you come across many such shells, the infestation has probably been going on in the background for quite a while. 

Indicators Of An Old Infestation Of Bed Bugs

Biodegradation of bed bug casings takes time. They can stay in a place for a long time because chitin, similar to old fingernails, does not rot. 

If these casings are left in a place with minimal disturbance, they can remain there for years. As such, the casings can indicate old infestations that could have since ended when they were left behind.

The shells do not necessarily mean there is a prevailing infestation. They imply that the space had bed bugs in the past. 

Signs Of Feeding Bed Bugs

Bites on your skin from bed bugs are not the only indication of feeding bed bugs. Discarded shells also show that the bed bugs have been feeding. 

A bed bug is utterly dependent on its host. Males will need to feed before mating, for instance, for energy generation to release sperm. Females, on the other hand, are required to feed before laying any egg, or they starve themselves of nutrients quickly. 

Similarly, a bed bug will need to feed before growing in its next stage in life. The bugs feed and digest for a day, and over this period, the gained nutrients go into increasing their size. 

The Lifecycle Of A Bed Bug

To better understand the meaning of bed bug shells, you should be familiar with the bed bug’s life cycle. 

1. Eggs

A female adult bed bug will lay translucent, white, and oval eggs in small spaces after mating. Each laid egg will have a length of one-sixteenth an inch and takes between six to ten days to hatch. The females lay up to 250 eggs during their lifetime, and white casings are left behind when the eggs hatch. 

2. First Nymph Stage

A bed bug must undergo five nymph stages before attaining full maturity. During the first nymph stage, they have a length of 1.5 mm. And upon hatching the nymph from the eggs, they immediately search for their initial blood meal. 

3. Second Nymph Stage

Bed bugs go through molting soon after having their initial blood meal. Upon shedding the exoskeleton, it has a length of approximately two millimeters.

4. Third Nymph Stage

The bed bugs continue feeding and will once again go through the molting process. After this second molting process, the bugs will have a length of approximately 2.5 millimeters. 

5. Fourth Nymph Stage

During this fourth nymph stage, the bed bug will have a length of approximately three millimeters. 

5. 5th Nymph Stage

This marks the final stage of a bed bug’s nymph. After this stage, the bed bug is now an adult. It undergoes its final molting process and emerges from it with a length of approximately 4.5 millimeters. 

7. Adult Bed Bug

The entire process takes approximately five weeks, from hatching the eggs to when the nymph turns into an adult. At the adult stage, the bed bug can finally breed and reproduce.

Note that following every stage of their lifecycle, the nymph will leave behind a shell. The shells will have different lengths depending on the particular molting stage. 

Bed Bug Casings: What Do They Look Like?

An old bed bug casing will look like a live bed bug. Notable features include the small legs, body, and larger abdomen. 

An old bed bug casing will look like a live bed bug.

The primary notable difference between the shell and a live bug is the more translucent appearance of the shell. This is because there isn’t a body inside it. A bed bug will get a significant opaque look following a meal when they are filled with blood. The rear end will become swollen, red, and longer

The shells are somewhat translucent without the bed bug’s body or blood inside. If you are keen enough, you can also notice the hole through which the bug escaped from the shell. 

Sizes Of Bed Bug Casings

Bed bug casings will not be of identical size as the actual bed bug. An adult will have roughly the same size as apple seeds, whereas fifth-instar bed bugs are considerably smaller. 

Nymph bugs have a size similar to a grain of rice. The shells are, as such, hard to notice. This is because they are not only tiny but also white.

And due to their reduced size, you can accidentally destroy them by crushing them. 

Other bugs’ instar shells have sizes ranging between this and an adult size. Upon progressing to the second and third instars, the shells become brown, meaning noticing them becomes easier. 

What Is The Color Of A Bed Bug Shell?

As earlier stated, bed bug casings are more translucent. That said, they have a noticeable brown color. The bug shell’s brown color is from the blood diet. This process can be seen in action since nymphs yet to feed have an off-white to white color. 

It is difficult to distinguish between a live bug and its old shell from just the color. Both have the same brown color. But since old shells have a more translucent look, the shade is lighter. 

What Do Shells Of Bed Bugs Feel Like

Bed bug casings are made of chitin which is a nail-like material. Nonetheless, this does not imply that it is tough to squash. You can easily squash them more if they have just had a meal. 

When a bed bug is unfed, it is tough, and the shell is rigid. Squashing and smearing it using a napkin is impossible, as you could do with a well-fed bug.

The chitin substance is tough and rigid and is widely available in nature. It makes up most bugs’ exoskeletons and also that of larger creatures such as crabs. It is ideal for light armor, such as bug shells.

In exoskeletons, chitin is usually found together with a rubbery, elastic material known as resilin. This facilitates movement and stretching of the joints and extension of the bug’s abdomen outwards. 


A bed bug will shed its exoskeleton multiple times during its various growth stages to create room for it to grow into mature adult bed bugs. Once they reach adulthood, they will not molt (shed the exoskeleton) again since they no longer need to grow.

You can tell a bug’s shell from a live bug on keen observation. The shell will have a lighter color and a hole through which the bug escaped the shell.