Jumping Spider Molting Guide
Molting is one of the most critical and vulnerable periods in a jumping spider's life. Understanding what to expect before, during, and after a molt helps keepers avoid the most common mistakes that lead to failed molts, injury, or death. This guide covers the full molting process for jumping spiders.
What Is Molting?
Jumping spiders, like all arachnids, have an exoskeleton that does not grow with them. To grow larger, they must shed their old exoskeleton entirely and expand before the new one hardens. This process is called molting (or ecdysis). Jumping spiders molt multiple times from spiderling to adulthood, and the frequency decreases as they mature.
How Often Do Jumping Spiders Molt?
Molting frequency depends on age, temperature, and feeding rate. Spiderlings molt frequently — sometimes every few weeks. Juveniles molt less frequently as they mature. Once a jumping spider reaches its final molt and becomes sexually mature, it will not molt again.
Pre-Molt Signs
Recognizing pre-molt behavior early helps you prepare and avoid disturbing the spider at a critical time.
- Reduced appetite or complete food refusal: One of the earliest and most reliable signs. A spider that suddenly stops eating after a consistent feeding schedule is likely entering pre-molt. Food refusal during pre-molt is normal — if your spider refuses food outside of the molting process, see our Jumping Spider Not Eating guide.
- Increased webbing: The spider may reinforce its sleeping sac or build a thicker, more sealed retreat.
- Sealing the sac entrance: A spider that seals itself inside a thickened sac and becomes inactive is almost certainly in pre-molt or actively molting.
- Darkening abdomen: In some species, the abdomen may appear darker or duller before a molt.
- Lethargy: Reduced movement and hunting activity in the days leading up to a molt.
The Molting Process
Once the spider has sealed itself in its sac, the actual molt typically takes 1–4 hours. The spider may lie on its back or side while shedding its old exoskeleton — this is completely normal and should not be mistaken for illness or death. The spider splits the old exoskeleton along the cephalothorax and slowly pulls itself free. After emerging, the spider will rest while the new exoskeleton expands and begins to harden.
It's normal to find the shed exoskeleton (called the exuvia) inside or near the retreat after a successful molt. This can often be used to estimate the spider's age or determine its sex by experienced keepers.
The entire pre-molt period — from food refusal to completed molt — can last anywhere from a few days to several weeks depending on the individual and species.
How Long Does a Jumping Spider Stay in Its Molt Sac?
Many jumping spiders remain inside their retreat for several days before and after molting. Even after shedding successfully, they often wait until the new exoskeleton has hardened before emerging. Avoid opening or disturbing the retreat during this time — what looks like inactivity is usually a normal part of the process.
What to Do During a Molt
- Do not disturb the enclosure. Avoid moving, tapping, or opening the enclosure while the spider is molting.
- Do not mist near the sac entrance. Flooding the sac during a molt can cause complications.
- Do not offer food. Live prey in the enclosure during a molt is dangerous. Remove any uneaten prey immediately if you notice pre-molt signs.
- Do not try to help. If a molt appears to be going slowly or the spider seems stuck, do not intervene. Interference almost always causes more harm than the molt itself.
After the Molt
After a successful molt, the spider's new exoskeleton is soft and vulnerable. The spider needs several days for the exoskeleton to fully harden before it can hunt safely.
- Wait at least 5–7 days before offering prey after a molt
- Offer a light misting so the spider can drink — molting is dehydrating
- Do not handle the spider until the exoskeleton has fully hardened
- The spider may appear paler or duller immediately after molting — coloration returns as the exoskeleton hardens
Failed Molts
A failed molt occurs when the spider cannot fully escape its old exoskeleton. This can result in lost limbs, deformity, or death. Failed molts can be associated with dehydration, injury, nutritional issues, improper environmental conditions, or underlying health problems.
How to reduce the risk of failed molts:
- Maintain consistent misting so the spider is well-hydrated going into a molt
- Remove all live prey from the enclosure at the first sign of pre-molt
- Never disturb the spider or its sac during the molting period
- Ensure the enclosure has appropriate humidity — not too dry
If a molt fails and the spider survives, it may recover partially depending on the severity. Missing legs can sometimes regenerate at the next molt in younger spiders, though this is not guaranteed.
Molting and Lifespan
Each molt carries some inherent risk. As jumping spiders age and approach their final molt, the risk of complications increases. A spider that has completed its final molt will not molt again — any exoskeleton issues after this point are permanent. See our Jumping Spider Lifespan guide for more on aging.