Why do insects molt during their development?
Written by
Julia Anderson
Reviewed by
Prof. Charles Hartman, Ph.D.Ecdysis is the process that allows insects to grow larger than their hard exoskeletons. As their shells are of a hard nature, they can only accommodate limited growth. Therefore, the old exoskeleton is shed, and a new, larger one is formed. This important process is under hormonal control and takes place in connection with the molting of all stages of life.
Hormonal Triggers
- Brain signals: Release neurohormones when growth pressure builds
- Ecdysone production: Prothoracic glands activate this molting hormone
- Timing control: Juvenile hormone levels determine molt type
- Environmental cues: Temperature and light influence hormone cycles
Physical Transformation
- Enzyme secretion: Dissolves inner exoskeleton layer
- New cuticle: Forms underneath old shell before splitting
- Ecdysis: Insect wriggles out through split exoskeleton
- Expansion: Body inflates using air or fluid intake
After an insect has molted, it is especially vulnerable, as the new, softer cuticle takes hours to harden. Insects spend this risky interval hiding from predators. Sclerotization hardens the new cuticle through the cross-linking of proteins. When insects fail to molt, they can become deformed or die.
Special adaptations lessen molting risk. Aquatic insects tend to molt while in contact with the water surface, allowing them to float. Cave species will select sheltered rock crevices. Certain ants will surround their molting colony members in a protective circle of workers. These behaviors highlight adaptive responses to the costs associated with growth.
The frequency of molting is a characteristic of individual development that typically decreases with maturity. Larvae molt more frequently than nymphs, while adults never molt after the final exoskeleton has hardened. This pattern in molting frequency reflects trade-offs between growth and survival risk throughout developmental stages, as individuals encounter growing indiscretions.
Read the full article: Insect Life Cycles: Types, Stages, and Facts
