How do bedbugs molt? - briefly
Bedbugs grow through five immature stages, shedding their rigid exoskeleton after each blood meal in a process called ecdysis; each molt expands the cuticle, allowing the insect to increase in size until it reaches adulthood.
How do bedbugs molt? - in detail
Bed bugs undergo a series of five molts before reaching adulthood. Each molt, called ecdysis, follows a precise physiological sequence.
The process begins when the insect’s endocrine system releases ecdysteroids, triggering the shedding of the old exoskeleton. The new cuticle, initially soft and translucent, is produced beneath the old one by epidermal cells that secrete chitin and protein layers. As the old cuticle separates, the bug expands its body by taking in air and water, increasing internal pressure to split the old shell along predetermined lines.
The actual emergence occurs in three observable stages:
- Pre‑ecdysis – the bug becomes less active, its abdomen swells, and the old cuticle loosens.
- Ecdysis – the insect contracts abdominal muscles to rupture the old exoskeleton, then pulls the front part of its body out, followed by the rear.
- Post‑ecdysis – the new exoskeleton hardens through sclerotization, a process that involves cross‑linking of cuticular proteins and deposition of melanin, providing rigidity and protection.
After each molt, the bug must locate a safe, concealed site. Typical refuges include mattress seams, cracks in furniture, or behind wall hangings. The insect remains immobile for several hours to allow the cuticle to fully harden and to avoid predation while vulnerable.
Molting frequency depends on temperature and food availability. At optimal indoor temperatures (22‑27 °C) and with regular blood meals, a nymph may complete an instar in 4–7 days. Cooler conditions extend the interval, sometimes to weeks, while starvation can halt development entirely.
The hormonal cascade that regulates molting involves:
- Prothoracicotropic hormone (PTTH) – released from the brain, stimulates the prothoracic glands.
- Ecdysone – produced by the prothoracic glands, converted to 20‑hydroxyecdysone, the active molting hormone.
- Juvenile hormone (JH) – maintains nymphal status; its decline after the final molt permits adult differentiation.
Disruption of any hormonal step—through chemical inhibitors or environmental stress—can cause incomplete ecdysis, resulting in mortality or malformed individuals.
In summary, bed bug molting is a hormonally driven, multi‑stage event that requires precise timing, a protected environment, and adequate nutrition. Each successful molt advances the insect to the next developmental stage, culminating in a reproductive adult.