How do insects molt?

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Molting is a complex and crucial process where insects and other arthropods shed their old exoskeleton and replace it with a new, larger one. It is vital for growth, development, metamorphosis, repair of injured body parts, and removal of waste or parasites. It also comes with several risks and increases the vulnerability of the insect during the molt.

If you want to know more about why insects molt, and the advantages and disadvantages of molting, check out this article.

As a whole, the molting process can be broken down into several stages. It starts with the initiation through hormones, and goes through various stages during the actual molt in which the old exoskeleton softens, breaks open, allows the insect to crawl out, and ends with the hardening of the new exoskeleton.

In the following, you will find information on each of the molting stages in detail.

Different stages of molting

Every insect goes through various stages of development. These stages are commonly called “instar” and the insect is called “nymph” until it reaches the stage after the last molt. After the last molt, the insect is an “adult” and is usually able to reproduce. Some insects change their appearance after every molt, and some only change after the last molt, developing wings, or different colors.

Pre-molting behaviors

The molting process is a complex one that is initiated by hormones. Before the insect can start to shed the exoskeleton, it needs to prepare itself for a safe molt. The preparations include finding a secure location, reduced feeding, reduced activity, secreting the molting fluid, and separation from the old exoskeleton.

Reduced Feeding

Before the actual molting starts, insects often reduce or even entirely stop feeding. The reason behind this behavior is, that the insect’s digestive system undergoes changes in preparation for molting. In order to molt properly, the gut needs to be as empty as possible.

Seeking a Safe Location

Molting is a risky process because the insect sheds the protecting exoskeleton and is incapable of moving during the entire process. This is why a safe location is very important to be able to molt in peace and without being attacked by predators that might take advantage of the weak state the insect is in. A safe location can be different for every insect. Some insects, such as praying mantis and walking sticks, dangle from leaves or branches and crawl out of the old skin while hanging upside down. Others, such as tarantulas, lay on the ground on their backs. Some burrow underground, others hide in crevices, or hide in their sheltered habitats.

Reduced Activity

As the molting process comes closer, the insect’s physical activity decreases drastically. They are less active and spend more time resting or staying in one place. It helps the insect to conserve energy and reduces the risk of injuring themselves before molting.

The insects that are about to molt are often restless or fidgeting. They might move their legs or antennae more frequently as they prepare for the shedding process.

Secreting Molting Fluid

One of the preparations for the molting process is the secreting of a molting fluid between the old and the new exoskeleton layers. The old exoskeleton is still around the body of the insect on the outside, and the new skin is still very soft under that outer layer. The fluid softens the old exoskeleton and thereby helps the insect to shed it during molting. Otherwise, the risk of getting stuck during the process would be a lot higher.

Shedding Old Exoskeleton

Once the insect is ready to molt, it releases enzymes that dissolve the connection between the old cuticle and the epidermis beneath. This allows the insect to shed the old exoskeleton.

Once all of the pre-molting behavior is successfully completed, the actual molting can start in which the insect crawls out of the old exoskeleton.

The Molting Process

Initiation of the molt

The molt is initiated through hormones when the insect’s body outgrows its current exoskeleton. The exoskeleton of insects is hard and does not grow with the insect, which is why it needs to be replaced once the insect outgrows it.

Softening of the exoskeleton

The old exoskeleton is still too hard for the insect to break through, which is why enzymes are secreted between the old exoskeleton and the layer beneath it. The enzymes help break down the old cuticle, making it softer.

Formation of the new exoskeleton

While the old cuticle softens, the insect creates a new, larger, but still very soft and flexible exoskeleton underneath the old one.

Separation from the old exoskeleton

When the old exoskeleton finally separates from the underlying epidermis, a gap forms. The insect continues to put pressure on the old cuticle to split the old exoskeleton.

Shedding of the Old Exoskeleton

Once the new exoskeleton is fully formed, the insect starts to push and wiggle the body to shed the old exoskeleton. The insect starts pushing its head and thorax forward, gradually crawling out of the old exoskeleton.

The insect carefully extracts legs, antennae, and other appendages from the old exoskeleton. It has to be very careful to avoid injuries on the new and still very soft exoskeleton.

This process can take anything between a few minutes, to several days, depending on the insect’s species, size, life stage, and environmental conditions such as temperature and humidity levels.

Expansion of new Exoskeleton

After successfully crawling out of the old exoskeleton, the insect slowly starts to expand the new exoskeleton to its full size.

Hardening and Darkening of Exoskeleton

Now that the actual molting process is successfully accomplished, the exoskeleton hardens and darkens to be as protective and supportive as the old exoskeleton.

The insect gradually regains its mobility and functionality after molting.

More information on molting

Information on molting pet tarantulas

Difference between a walking stick and a praying mantis

How big do praying mantis get?

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