Tarantula Premolt – Complete Care Guide

Experiencing tarantula premolt for the first time can be a little stressful and concerning. Especially if there are any sudden behavior changes! There’s no need to be concerned however, this is a natural process and your tarantula will go through this semi-regularly for most of their life.

If your tarantula starts displaying signs of premolt, it’s best to leave them alone until after they’ve molted and hardened. Bothering them during this time causes additional stress which increases the time they spend in premolt. It also increases the chance of something going wrong during the molt.

Tarantula premolt is an exciting time for all tarantula keepers though it can be stressful at times. We aim to ease your concerns about the premolt period tarantulas go through and get you as excited as we are about it!

What is Tarantula Premolt?

In tarantula keeping, “premolt” is the term used to describe the time before a tarantula molts their exoskeleton. All invertebrates, such as tarantulas and other arachnids, all go through this natural growing process. It’s nothing to be worried about as your tarantula needs to molt so they can grow bigger.

Premolt is the time before the tarantula begins to molt. This means they are preparing to leave their old exoskeleton and will want you to leave them alone for a little while.

Why do Tarantulas go into Premolt?

As a tarantula, growing takes effort. All invertebrates have an exoskeleton that protects them but, this exoskeleton doesn’t grow with them. This means they need to molt or shed the old exoskeleton once they get too big for the current external one to house them. It’s all part of the natural tarantula growing process.

Premolt is the stage before the molt takes place. When a tarantula is preparing to molt, a behavior change is expected. A freshly molted tarantula is vulnerable so a tarantula in premolt is starting to prepare for this.

Signs your Tarantula is in Premolt

There are several ways to tell when your tarantula is entering premolt. Some tarantulas might be less obvious about it than others but these are the potential signs a tarantula is entering premolt.

1. Big and/or shiny Abdomen

Most tarantulas ready for premolt will have a large plump abdomen that could be up to 1.5 times the size of their carapace. In some cases, it could be even larger! As the area is stretched, it causes the abdomen to look shiny. Slings (spiderlings) will look much shinier in premolt than older tarantulas.

2. Low Appetite

This is the most obvious and common sign of premolt. Tarantulas will typically stop eating in premolt and some might suddenly stop showing interest in food as the molt approaches. However, this isn’t always a sign of premolt so keep an eye out for other possible tarantula premolt signs.

3. Darkens in Color

Due to the new exoskeleton forming under the old one, they might start to look a little darker as the time to molt draws near. This is especially evident on the abdomen in slings that might have a dark spot on them. Species that kick a lot of urticating hairs will also show this more obvious.

4. Tarantula seems ‘slow’ or stays still

Becoming more lethargic is a classic behavioral sign for tarantula premolt. This is much easier to spot in species and individuals who are normally more active like to roam the enclosure or move fast. In premolt, they become more sluggish and will prefer to sit in one spot such as hiding away.

5. Buries themselves in den

Tarantulas in premolt have also been seen hiding away in their den and sealing up the entrance with webbing, soil or whatever they can move. They are not in danger and they do not need you to rescue them. The tarantula just wants some privacy and security while they molt.

6. Tarantula is on their back

If your tarantula is on their back, do not touch them! They do not need help and moving them will interrupt the molting process. Flipping the spider over, blowing on it or spraying them with water will harm them. Tarantulas flip onto their back when they begin to molt.

7. Increased Web Production

Tarantulas usually molt on an area covered in webbing since this protects the tarantula. They will lay down layer after layer of webbing in a small area which is a sign the tarantula will molt very soon. Some species may even kick hairs onto the web for extra protection.

How Long does the Tarantula Premolt Phase Last?

There is no time limit for how long a tarantula might be in premolt before they finally decide to molt. This means some tarantulas might spend a few days like this while others could take several months before they molt. It depends on the species and the individual tarantula.

Once a tarantula is ready to molt, the process doesn’t take too long. There’s a good chance you won’t even see it when it happens and will just find an old exoskeleton from the molt. The premolt period is much longer than the actual molt. Premolt duration depends on your tarantula and the duration typically increases as they get older.

What does a Spiderlings Premolt Phase look like?

Slings grow much faster than older tarantulas so they will be molting more often. This also means that spiderlings spend more time in premolt and will enter it on a more regular basis. 

Spiderlings act similar to older tarantulas when they enter premolt but there are some minor differences. While all tarantulas will experience a swollen abdomen, a Slings abdomen will look especially large during premolt. Spiderlings will also have a much shiny abdomen which is more likely to also look darker than normal compared to an older tarantula.

Tarantula Behavior During Premolt

Older tarantulas can experience various visible and behavioral changes during this time of their life. As tarantulas get older, their growth may slow which means they will enter premolt less regularly and molt less. How they react to premolt can vary according to species and on an individual level too.

The signs listed above are standard across all tarantula species though not all individuals will display each of them. Some tarantulas might eat one day, go into premolt overnight and molt the old exoskeleton within hours. Others might refuse food for months before they finally molt and some tarantulas might even close the entrance to their den and hide inside for over 6 months.

Premolt means a tarantula is getting ready to grow which makes them vulnerable. Behavior changes should be expected and should not be a cause for concern. Visual changes such as a swollen abdomen or darker coloration should also be expected.


A sudden behaviour shift can be scary for any new tarantula keeper to see. Especially if the tarantula is refusing to leave their den and closed off the entrance. You mustn’t panic and try to force the tarantula to do the things you think they should be doing such as moving around or eating. In truth, it’s best if you just leave the tarantula alone during this time to avoid causing them stress or accidental damage after they molt.

The tarantula naturally knows what they need during premolt. If they are hiding it means they want to be left alone so you must not bother them. Causing them distress during this period puts their life at risk and can delay the molt.

Written by:


Stuart is the editor of SpiderAdvice.