Why Is My Tarantula Not Eating Before Molting What To Expect

Tarantulas are fascinating creatures, admired for their quiet demeanor and unique life cycles. One of the most critical phases in a tarantula’s life is molting—the process by which it sheds its exoskeleton to grow larger or repair damage. If you’ve noticed your tarantula refusing food, especially over an extended period, it’s likely preparing to molt. This behavior is completely normal, but understanding why it happens and what to expect can ease concerns and help you provide optimal care.

Molting is both a natural and vulnerable time for tarantulas. During this phase, their bodies undergo significant internal changes that require energy and rest. Appetite suppression is just one part of a broader physiological shift. Recognizing the signs, knowing how long fasting typically lasts, and avoiding common mistakes can make the difference between a successful molt and potential complications.

Understanding Pre-Molt Fasting: The Biology Behind the Fast

Tarantulas do not eat before molting because their bodies are redirecting energy toward producing a new exoskeleton. Unlike mammals, arachnids have external skeletons made of chitin, a tough, rigid substance that doesn’t stretch. To grow, they must shed this outer layer entirely—a process that demands substantial metabolic resources.

In the weeks leading up to molting, a tarantula enters a pre-molt phase known as ecdysis preparation. During this time, digestive processes slow down significantly. The old inner lining of the gut begins to detach and will be expelled during the molt. Eating during this stage could lead to undigested food rotting inside the body, increasing the risk of infection or even death.

The spider also becomes less active, often retreating into its hide or webbing itself into a secluded spot. Some species may stop drinking water altogether for several days prior to molting. This reduced metabolism is part of a survival strategy honed through evolution—minimizing movement and consumption reduces stress on a body undergoing major structural change.

“Pre-molt fasting isn't a sign of illness—it's a necessary pause in the tarantula’s routine. Interpreting it as such prevents unnecessary interventions that could disrupt the process.” — Dr. Elena Ramirez, Arachnid Physiologist, University of Arizona

How Long Do Tarantulas Stop Eating Before Molting?

The duration of pre-molt fasting varies depending on the species, age, size, and environmental conditions. However, general patterns exist:

• Spiderlings (juveniles): May stop eating 1–2 weeks before molting.
• Sub-adults: Typically fast for 2–4 weeks.
• Adults: Can go without food for 4–8 weeks or longer, especially females of larger species.

Larger tarantulas, such as Theraphosa blondi (Goliath birdeater) or Aphonopelma chalcodes, often exhibit prolonged fasting periods. This is due to the complexity of rebuilding a more massive exoskeleton and associated tissues. In some documented cases, adult females have fasted for over three months before initiating a molt.

Tip: Never force-feed a tarantula showing pre-molt signs. Doing so risks regurgitation, internal injury, or fatal stress.

Key Signs Your Tarantula Is Entering Pre-Molt

Recognizing early indicators helps prevent misdiagnosis of health issues. Watch for these behavioral and physical cues:

1. Loss of appetite: Refusing prey items consistently over multiple feedings.
2. Reduced activity: Spending more time motionless, often in a curled position.
3. Webbing behavior: Creating thick mats of silk in the enclosure—this forms a protective platform for molting.
4. Dull coloration: The exoskeleton may appear faded or cloudy, especially around the carapace.
5. Visible bald spot: In some New World species, a hairless patch on the abdomen (used for defense) may look thinner or absent.
6. Drinking less: Reduced interest in water droplets or decreased visits to the water dish.

Not all tarantulas display every sign, and some species are more secretive than others. For example, arboreal tarantulas like Avicularia avicularia may retreat into their cork bark tubes and remain hidden for weeks.

What to Expect During and After the Molt

Once the pre-molt phase concludes, the actual molting event usually occurs at night or during low-light conditions. The entire process—from lying upside down to emerging from the old exoskeleton—can take anywhere from 30 minutes to several hours, depending on size and species.

After shedding, the tarantula will lie motionless on its back or side while its new exoskeleton hardens. This post-molt phase, called post-ecdysial quiescence, is extremely delicate. The new cuticle is soft and vulnerable, and the spider cannot walk properly yet. It may take days to weeks for full recovery, during which feeding should be avoided.

During this time, the tarantula reabsorbs fluid from the discarded exuvia (the old skin), recycling valuable proteins and minerals. Eventually, it flips upright and begins grooming itself. Only after the fangs (chelicerae) darken—indicating sclerotization—is it safe to offer food again.

Phase	Duration	Care Guidelines
Pre-Molt	1–12 weeks	Do not disturb; maintain humidity; remove uneaten prey
Molting Event	30 min – 3 hrs	Observe only; never intervene unless drowning risk exists
Post-Molt Recovery	1–3 weeks	No feeding; ensure hydration; avoid handling

Common Mistakes to Avoid During Pre-Molt

• Offering food too soon after the molt: Premature feeding can cause the tarantula to bite into its own soft limbs or rupture internal organs.
• Disturbing the enclosure: Moving substrate or decor can damage the silk mat essential for proper molting posture.
• Over-misting: While humidity is important, excessive moisture increases mold risk and can drown a molting spider lying on its back.
• Removing the exuvia: Leave the shed skin intact—it confirms a successful molt and provides insight into health.

Mini Case Study: A First-Time Owner’s Experience with Pre-Molt Fasting

Jamie adopted a juvenile Brachypelma smithi (Mexican redknee) from a local breeder. For the first six weeks, the tarantula ate well—consuming small crickets weekly. Then, abruptly, it refused all food. Alarmed, Jamie researched online and found conflicting advice: some forums suggested starvation was dangerous; others mentioned molting.

Observing closely, Jamie noticed the spider had started laying down dense webbing in one corner of the terrarium and appeared less active. After consulting a reputable care guide and joining a tarantula enthusiast group, Jamie decided to wait and monitor. Four weeks later, the tarantula flipped onto its back. Over the next two hours, it slowly extracted itself from the old exoskeleton. Two weeks passed before it drank again, and nearly three weeks before accepting a tiny cricket. The experience taught Jamie the importance of patience and recognizing natural behaviors over reactive assumptions.

This case illustrates how easily concern can turn into intervention—but also how observation and education lead to better outcomes.

Step-by-Step Guide: Supporting Your Tarantula Through Pre-Molt

If you suspect your tarantula is entering pre-molt, follow this timeline-based approach to support a healthy transition:

1. Week 1–2 (Early Pre-Molt): Remove any live prey left uneaten. Continue offering water via a shallow dish. Note any changes in behavior or appearance.
2. Week 3–4 (Mid Pre-Molt): Slightly increase humidity by misting one side of the enclosure (avoid direct spray). Do not clean the tank or rearrange decor.
3. Week 5+ (Late Pre-Molt): Cease all disturbances. If the spider has built a molting mat, do not touch it. Monitor remotely if possible (e.g., via phone camera).
4. D-Day (Molting): If the spider lies on its back, do not flip it. Only intervene if it appears stuck in water or submerged. Wait until it stands upright before resuming normal checks.
5. Post-Molt (Days 1–14): Keep the enclosure quiet. Offer a fresh water dish daily. Wait until the fangs turn black before attempting to feed.
6. Feeding Resumption: Start with small prey (e.g., pinhead crickets). Gradually return to regular feeding schedule over 2–3 meals.

Tip: Mark the date of the last meal in a journal. This helps track fasting duration and anticipate future molts based on growth patterns.

Frequently Asked Questions

How can I tell if my tarantula is sick or just in pre-molt?

Sick tarantulas often show abnormal leg curling (beyond mild tucking), lethargy combined with dehydration (shrunken abdomen), or uncontrolled falling. Pre-molt spiders remain alert when disturbed and maintain plump abdomens. If the spider responds defensively to gentle provocation (like a soft brush with a paintbrush), it’s likely healthy and preparing to molt.

Should I remove the old exoskeleton after molting?

No. Leave the exuvia in place. It serves as proof of a complete molt and allows you to check for missing limbs or irregularities. Removing it risks disturbing the recovering spider. After several weeks, it can be carefully removed during routine cleaning—if still present.

Can tarantulas die during molting? What increases the risk?

Yes, molting carries inherent risks. Common causes of failure include low humidity (leading to desiccation), poor nutrition prior to molt, old age, or underlying health issues. Juveniles generally molt successfully more often than adults. Ensuring proper hydration and minimizing stress beforehand improves survival odds significantly.

Final Checklist: Preparing for a Successful Molt

Use this concise checklist to ensure your tarantula receives ideal care during the fasting and molting phases:

• ✅ Remove uneaten prey to prevent pest infestations
• ✅ Maintain stable temperature (75–80°F / 24–27°C)
• ✅ Provide moderate humidity (varies by species; ~60–75%)
• ✅ Avoid handling or tapping the enclosure
• ✅ Keep a journal of feeding and behavioral changes
• ✅ Have a shallow water dish available at all times
• ✅ Wait 2–3 weeks post-molt before offering food

Conclusion: Patience and Observation Are Key

When your tarantula stops eating, the most important thing you can do is nothing—except observe. Fasting before molting is not a malfunction or emergency; it’s a vital, evolved adaptation. By understanding the biological reasons behind this behavior and learning to recognize the signs, you empower yourself to provide calm, informed care.

Tarantulas thrive under consistency and minimal interference. Resist the urge to “fix” what isn’t broken. Instead, focus on creating a stable environment, documenting changes, and trusting the process. Each molt represents growth—not just for your spider, but for you as a keeper.

💬 Have a molting story or question? Share your experience in the comments below—your insights could help another tarantula owner navigate this crucial phase with confidence.