How does a bug shed its skin? - briefly
Insects produce a new, soft exoskeleton beneath the existing one, release enzymes that detach the outer layer, and then wriggle out of the old cuticle. Once free, they inflate their bodies and harden the fresh shell through a tanning process.
How does a bug shed its skin? - in detail
Insects replace their exoskeleton through a process called molting, or ecdysis. The event begins when the endocrine system releases ecdysteroids, primarily 20‑hydroxecdysone. These hormones trigger the epidermal cells beneath the old cuticle to produce a new, soft chitinous layer. Simultaneously, enzymes such as chitinase and proteases digest the inner portion of the existing exoskeleton, creating a space for expansion.
The animal then contracts its body muscles, raising internal pressure that splits the old cuticle along predetermined lines called ecdysial sutures. The insect emerges, still encased in a thin, translucent membrane known as the exuviae. At this stage the creature is vulnerable; the new cuticle lacks full sclerotization and is prone to dehydration.
To harden the fresh exoskeleton, the insect undergoes several steps:
- Expansion – intake of air or water inflates the body, allowing growth and reshaping of appendages.
- Tanning – phenoloxidase enzymes cross‑link cuticular proteins, increasing rigidity and pigmentation.
- Sclerotization – deposition of quinone compounds further strengthens the cuticle and reduces permeability.
- Cuticle shedding – the residual exuviae are rubbed off using legs or mouthparts, often leaving a characteristic “shell” behind.
Timing of these phases varies among species. Rapid growers, such as many larval insects, may complete ecdysis within a few hours, while larger or more complex insects can require several days for complete hardening. Environmental factors—temperature, humidity, and availability of nutrients—directly influence hormone levels and thus the rate of the entire sequence.
Overall, molting enables insects to increase in size, replace damaged tissue, and transition between life stages, such as from larva to pupa or from pupa to adult. The coordinated hormonal cascade, enzymatic digestion, and mechanical expansion constitute the complete mechanism by which an insect sheds its skin.