Why do insects molt?

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Insects are fascinating creatures with astonishing appearances and ways of living. The process of molting is a substantial part of their development in which they undergo a remarkable transformation, crawling out of their old exoskeletons in order to grow.

As a whole, insects molt due to four main reasons: Growth, regeneration, metamorphosis, and removing parasites. An insect can only develop and grow by molting because their exoskeleton does not grow with the insect.

In the following, you will find detailed information on why insects molt, how insects molt, as well as some disadvantages of molting. Let’s dive right into the fascinating world of molting insects.

Why do insects molt?

Molting is an essential part of an insect’s life. When insects molt, their exoskeleton breaks open, allowing the insect to crawl out of the old skin. It allows the insect to grow, regenerate, go through metamorphosis, and remove waste or parasites by shedding the outer layer of the body.

A synonym for the molting process is “ecdysis”. This word comes from the ancient Greek word “ἐκδύω” (ekduo) which can be translated as strip, unclothe, or take off.

Once the molting process is successfully completed, the insect has a soft exoskeleton before it hardens and provides the necessary support and protection.

The main reasons for molting are growth and development, regeneration and repair, metamorphosis, and the removal of waste and parasites.

Growth and Development

Insects have a hard skin, which is called the exoskeleton. It provides the insect with support and protection. Unlike human skin, this exoskeleton is rigid and does not grow with the insect. As the insect grows, the exoskeleton becomes too small for the insect and restricts further development. In order to further develop, the insect needs to molt and produce a new, larger exoskeleton that suits the new size.

With every molt, the insect grows until the last molt which leads to the adult stage. In this stage, an insect is able to reproduce and does not change its appearance or size anymore.

Regeneration and Repair

During a molt, the insect sheds its exoskeleton including any damaged or injured body parts. The insect that crawls out of the old skin can not only replace the potential damages. Even body parts such as a leg or an antenna can be repaired or even completely replaced. Internal tissues and organs may also be regenerated, but in some cases, it might need more than one molt for bigger injuries.


Many insects change their appearance through different life stages. Most insects start as larvae, develop into pupa, and end their development as adults. Insects such as walking sticks develop wings during their last molt. Other insects such as butterflies, beetles, and flies also undergo complete metamorphosis, and each development requires molting to transition to the next life phase.

Removal of Waste and Parasites

Some insect species are often faced with external parasites on their exoskeletons or accumulated waste. Molting can help them to get rid of these unwanted elements, maintaining overall health and cleanliness. There are parasites that need several hours to get through the exoskeleton and if the insect manages to molt before that happens, the parasites won’t even to able to have an impact on the insect.

What are the disadvantages and risks of molting?

Even though molting is a crucial process in the life of an insect, it comes with several disadvantages and risks. The main disadvantages are vulnerability during and right after the molt, energy cost, time consumption, and potential injuries or even failure of molting.


During the molting process, insects are very vulnerable. They don’t only lose the protection provided by their exoskeleton, they are also almost unable to move or defend themselves during the process. Predators can take advantage of this weakened state.

Energy Cost

Molting is a process that costs a lot of energy.

In order to be able to successfully complete the molting process, they need to stop eating before the molting starts. The process itself can take up to several days in which the insect does not eat either. Right after the molt they need to rest and wait for the new exoskeleton to harden. Only then can they eat again.

For insects that are kept as pets, such as praying mantis, spiders, walking sticks, etc. this might not be an issue. But insects in the wild can be challenging when food resources are scarce and they are not able to fill up their energy resources quickly enough. In that weakened state they are very vulnerable to predators.

Time Consumption

Depending on the insect, the size, the life stage, and environmental conditions such as temperature and humidity, the molting process can be a very time-consuming thing to do. In some cases, it only takes a few minutes, in other cases, it can take up several hours or even days to successfully complete the molting process. During the entire time, the insect can barely move, let alone defend itself.

Injuries and Failure of Molting

Molting can help an insect to repair and even replace injured body parts, but it can also lead to injuries. Sometimes insects have issues crawling out of the exoskeleton and get stuck. A low humidity level can lead to a quickly hardening exoskeleton, which can make it harder or even impossible for the insect to get out. Insects can get hurt, lose body parts, or even die during the molting process.

If you want to know more about the process of molting, check out this article on “How do insects molt

In this article, you can find information on molting pet tarantulas: https://animal-knowledge.com/everything-you-need-to-know-about-molting-pet-tarantulas/

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