How Do I Know If My Tarantula Is Going To Moult?

One of the most challenging parts of keeping a pet tarantula is caring for it before, during and after a moult.

A pet tarantula is at its most fragile when it moults, and if there are going to be complications when keeping tarantulas it almost always occurs during a moult.

So the next obvious question is how do you know if your tarantula is going to moult, and what should you do when you see the signs?

Signs of a Moulting Tarantula

There are five different signs which may suggest that your tarantula is going to moult. Not all spiders will display all four of these symptoms, but the more you see, the more likely a moult is on the horizon.


The first, and most guaranteed, sign that your pet tarantula is going to moult is that it goes off its food.

Assuming that all the environmental conditions are correct (temperature and humidity) then a tarantula which goes off its food is almost certainly coming up for a moult.

If you feed your spider a couple of times and find they have little or no interest in food then there is a very good chance that a moult is coming up.

Darkening Abdomen

Many of the most popular pet tarantulas have “urticating hairs” on their abdomens. These are defensive hairs which are kicked off when your tarantula is frightened or angry.

In reality many tarantulas which possess such hairs will kick some of them off, especially if they are regularly handled. This leads to a “bald spot” which is typically quite light in color.


When a tarantula gets close to a moult this bald patch will turn from a light yellow/pink/orange do a dark and glossy black as the new skin starts to form underneath.

A darkening abdomen is therefore an almost guaranteed way to spot a tarantula that will be moulting in the next few weeks.

Note, however, that not all species of tarantula actually have urticating hairs, so if your spider has no bald spot then this method cannot be relied upon.

Swollen Abdomen

This is not the most “scientific” of methods but tarantulas moult when they need to grow. Their legs and carapace are both tough and solid, but the abdomen of a tarantula is like an expanding sack. The more they eat, the bigger this abdomen gets.

Therefore when you see a tarantula – especially a growing (non-adult) specimen – that looks like its going to burst it is likely that a moult may be on the horizon. Some growing specimens can look almost like their abdomen is going to pop its so big and fat, and this can be the motivation that a tarantula needs to moult.

If ever you have a juvenile tarantula that looks so big that its going to “pop” then a moult in likely imminent.

Sluggish Behaviour

tarantula moulting photo

It takes a lot of effort and energy for a tarantula to change its skin, and most specimens will quietly prepare for this major event some weeks in advance. By the time of the actual moult, a spare and pliable skin will have been constructed underneath the current skin.

For this reason many tarantulas will become more sluggish before a moult. They’ll be less inclined to climb about, and more likely to sit about in a corner somewhere, seldom moving and instead focusing their energy on constructing their new skin.

If a typically active tarantula seems unwilling to move about all of a sudden then this may indicate that a moult is imminent.

Note: this sluggish behaviour should be coupled with one or more of the other signs described here. If your spider hasn’t stopped eating, or the bald patch hasn’t gone black, for example, then sluggishness could be a sign of more serious health issues.

Extra Webbing

Your tarantula is at its most vulnerable when going through a moult. With their soft skin and fangs, a recently moulted tarantula is unable to defend itself in the wild.

For this reason many tarantulas will sink deep into their lair and cover the entrance hole with web as a source of protection.

If your spider is one that naturally produces a fair amount of webbing (such as the Cobalt Blue or Green Bottle Blue) and you suddenly find that they have concealed themselves behind a piece of cork bark, with no entry or exit holes, this too can be a strong indicator that moulting is on the horizon.

What Should I Do When My Tarantula Is Moulting?

So you’ve seen one or more of the above signs and are feeling confident that your pet tarantula is coming up to moult. We’ve also discussed how its critical to get this moulting process right for your pet. So what should you, as the owner, do to help prepare your pet for a perfect moult?

Withold Food

tarantula moulting photo

First and foremost it is important to appreciate that tarantulas won’t (or can’t) eat for a week or two before and after a moult. Indeed, insects such as crickets running around the tank can cause injury and annoyance to a tarantula that is trying to moult.

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If the signs suggest that your spider is going to change its skin, therefore, it makes sense to withhold food for a period of time to prevent this potential source of damage.

Ensure Suitable Hides Are Present

As stated previously, tarantulas like to moult in privacy where they feel safe. As a result you should ensure that your pet has suitable hide(s) where it can conceal itself when a moult seems imminent.

Increase Humidity

One of the most critical aspects for a successful moult is suitable humidity. Tarantulas that try to change their skin in an overly-dry environment frequently struggle, sometimes to their own detriment.

When your tarantula is coming up to moult it can therefore be a good idea to increase the humidity. Spraying the tank with tepid water, or gently misting the substrate, can both be excellent ways to increasing the humidity in your tarantula cage.

Provide Privacy

Lastly, it is important to give your pet the privacy they desire. For example if they have webbed themselves into their lair then don’t be tempted to peel back the web to check on your spider. Avoid handling them, and give them the peace and quiet they need during this critical period.

How Do I Know If My Tarantula Has Moulted?

If the signs are well, and you have suitably prepared your tarantula, then some weeks later you should find that your tarantula has successfully moulted.

For the first-time tarantula keeper of course it can be a worrying first experience; so how do you know for certain that your spider has successfully moulted?

Sloughed Skin

tarantula skin photo

The most obvious sign that your tarantula has moulted is the presence of their old skin. It is not unheard of for keepers to initially think they have two tarantulas in the cage until they realize one of them is simply the sloughed skin. Even through thick webbing it is often possible to see this discarded skin.

Spotting an old skin is easiest in those species, such as Brachypelma smithi or Grammostola rosea, who often moult in the open. For more secretive spiders, however, you may not always see the old skin immediately as it could be down a hole or tucked behind some cork bark.

Be aware, therefore, that just because you haven’t seen a skin (yet) doesn’t necessarily mean that your spider hasn’t yet moulted.

Odd Stretching

Once a spider moults they will normally spend a few days making sure that their new skin has hardened correctly. They do this by stretching the limbs and pushing fluids through them, in order to expand them to their full dimensions.

Another sign, therefore, that your tarantula has successfully moulted can be seeing them sitting in odd positions. Often legs will be stretched out directly infront and behind your spider, rather than sitting casually by their sides.

If you look at your spider and find they look like they’re doing “tarantula yoga” this can be a further indication that a moult has been successfully completed.

Brighter Colors

tarantula orange photo

Possibly the most obvious visual queue that your spider has moulted is that they look amazing.

That bald patch will be gone, your tarantula’s hair will look silky-smooth and all their colors will seem brighter and more vibrant.

The first species of tarantula which I personally bred was Brachypelma vagans, a species which remains close to my heart even today.

Every time one of my specimens moults I am truly blown away by their glossy black legs and bright scarlet abdomen – truly a sight to behold!

Color Changes

Many juvenile tarantulas look completely different to adult specimens.

As the juvenile moults it will slowly take on the colors of the adults, getting ever closer to the final appearance as they moult.

Therefore if you peer into your spider cage one day to find that your pet has changed its colors, this too is a strong signal that a moult has occurred.

Greater Activity

Finally, a spider that has moulted and hardened off its skin successfully will find itself tremendously hungry after some weeks of fasting. This can result in a noticably more active tarantula.

If your spider has been holed up for weeks, unseen to you, and then one evening you find them bounding around the cage it is generally safe to assume that a moult has occurred, especially if this activity is paired with one or more of the other signs described.

What Happens After A Moult?

tarantula orange photo

So by now you’re feeling pretty proud of yourself. You spotted that a moult was imminent, you prepared your spider suitably and now here they are – bigger, brighter, more active and more colorful than ever before. Great job!

So what happens next?


Firstly, I like to give my spiders about a week to recover before I start to offer food again. Pop in just one or two of your chosen feeder insects and watch for a response.

Your spider should be hungry by this point so should pounce immediately on the food. If so, you’re all set. Just start feeding again as you always have done.

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On the opposite end of the scale your spider may show little or no interest. Alternatively it may even run away from the food. If this is the case, remove the prey and try again some days later.


When you’re confident that your tarantula has returned to normal, it is smart to remove the old skin from the cage. Leaving it in there not only looks unsightly, but can also attract parasites or mould which feeds on the dead skin.

If necessary, especially for arboreal or aggressive species, use a long pair of metal forceps to gently remove the skin from the cage.


If you are keeping juvenile tarantulas then moulting can be an ideal time to consider sexing your spider. Firstly, try to familiarize yourself with what an adult male tarantula looks like.

This is important as adult males have a very short lifespan, so if you want to try and mate your spider its critical to be able to identify a male as soon as he has matured.

Secondly, the moulted skin which you removed can also be a useful tool for sexing your spider. Whether you learn to do this yourself, or rely on the services of an expert, if you’re rearing young tarantulas then a careful inspection of the moulted skin will help you decide whether you have a male or female – and so potentially prepare for breeding campaigns in the future.


Lastly it can be interesting and beneficial to keep a record of moults. Adult tarantulas, for example, typically only moult once a year and do so at roughly the same time. Therefore keeping a note of when your spider last moulted can help you in predicting when the next moult will likely arise.

For growing juveniles which moult far more regularly it can still be worthwhile keeping a record, as over time you’ll start to see patterns develop which will help you predict forthcoming moults. You’ll also be doing your own little bit of biological research which has value in itself for the hobby.


How often to tarantulas moult?

Adult tarantulas typically moult once per annum, at roughly the same time each year. It is important to note, however, that most adult male tarantulas won’t moult again once they reach maturity.

While adult females may live for decades, the males typically only survive for 12-18 months after maturity hence the lack of supplementary moults.

Spiderlings and juveniles moult far more frequently, though how often they moult is directly correlated with how much they eat; the more they eat, the sooner they will moult. In addition it is worth noting that some tarantula species grow much more rapidly than others, meaning they will moult more frequently.

In general you can expect juvenile tarantulas to moult once every few months, with the period of time between moults getting longer as the spider nears maturity.

How long does it take a tarantula to moult?

While tarantulas often take some weeks preparing for a moult, the actual process of changing the skin is relatively brief, and is measured in hours. Note, however, that once a tarantula has removed itself from the old skin it will still take some days before the skin is properly hardened and the tarantula is able to begin feeding once again.

When do tarantulas moult?

Tarantulas are nocturnal, so it is most common for them to moult at night. It is not unusual to wake up early in the morning to find your tarantula part way through a moult, and some may even moult during daylight hours. The important point is to give your spider the privacy it needs during this difficult phase.

So, if you wake up in the morning to find your spider part way through a moult try not to disturb them with loud noises or bright lights. Instead, leave them well alone and soon enough you’ll find your tarantula sitting next to its recently-sloughed skin.

Photos c/o Distres_, Furryscaly, shi-qi

Richard Adams

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