Understanding Molts

One of the Most Important Events in a Spider's Life

If there is one process every jumping spider keeper should understand, it is molting.

Molting is a natural and essential part of a spider's development. Unlike mammals, spiders cannot grow continuously. Instead, they periodically shed their entire exoskeleton and emerge larger than before.

For new keepers, a molt can be both fascinating and nerve-wracking. A spider may stop eating, disappear into its hammock for weeks, and suddenly seem inactive. While these changes can appear alarming, they are often signs that everything is proceeding normally.

Understanding the molting process is one of the most important skills a keeper can develop.

What Is Molting?

Molting, also called ecdysis, is the process of shedding an old exoskeleton.

Because a spider's exoskeleton cannot expand, growth occurs through a cycle of:

  1. Developing a new exoskeleton beneath the old one

  2. Shedding the old exoskeleton

  3. Expanding and hardening the new exoskeleton

Every jumping spider will molt multiple times throughout its life.

Why Do Spiders Molt?

Molting allows a spider to:

Grow Larger

The primary purpose of molting is growth.

Replace Damaged Structures

Lost hairs, damaged body parts, and worn exoskeleton components may be renewed during future molts.

Reach Maturity

Each molt brings the spider closer to adulthood and reproductive maturity.

How Many Times Will a Spider Molt?

The exact number varies by species and individual genetics.

Most jumping spiders undergo:

7–12 molts

before reaching adulthood.

Larger species often experience more molts than smaller species.

Understanding Instars

Spider keepers often refer to developmental stages as:

Instars

Each instar represents the period between molts.

For example:

  • i2 = Second instar

  • i5 = Fifth instar

  • i8 = Eighth instar

As the instar number increases, the spider becomes larger and more mature.

Premolt: Preparing for a Molt

Before shedding its exoskeleton, a spider enters a phase known as:

Premolt

Premolt can last days or even weeks depending on age and species.

Common Premolt Signs

Food Refusal

One of the most obvious signs.

A spider that normally eats enthusiastically may suddenly refuse prey.

Increased Webbing

The spider often reinforces its hammock or creates a thicker retreat.

Reduced Activity

Exploration decreases.

The spider spends more time resting.

Extended Hiding

Many spiders remain inside their retreat for prolonged periods.

Darkening Coloration

In some individuals, colors may appear darker as the new exoskeleton develops beneath the old one.

The Molting Retreat

Most jumping spiders construct a special hammock before molting.

This retreat serves as:

  • Protection

  • A resting area

  • A secure molting chamber

Once a spider enters this stage, disturbance should be minimized.

During the Molt

The actual molt often occurs while the spider is suspended within its hammock.

During this process:

  • The old exoskeleton splits

  • The spider slowly emerges

  • Legs are carefully withdrawn

  • The new exoskeleton expands

This process may take several hours.

Never Disturb a Molting Spider

This cannot be emphasized enough.

Do Not:

✗ Open the retreat

✗ Attempt handling

✗ Force feeding

✗ Move the spider

✗ Rearrange the enclosure

A disturbance during molting can cause serious injury or death.

Postmolt Recovery

After emerging, the spider is extremely vulnerable.

The new exoskeleton is:

  • Soft

  • Flexible

  • Easily damaged

The spider requires time to harden before returning to normal activity.

Why Freshly Molted Spiders Look Different

Many keepers notice dramatic changes after a molt.

Common changes include:

Increased Size

The spider often appears noticeably larger.

New Coloration

Colors may become brighter or more defined.

More Pronounced Patterns

Markings may become clearer.

Sexual Characteristics

As maturity approaches, adult coloration and features often begin to appear.

Feeding After a Molt

Patience is important.

Wait until:

✓ The spider becomes active

✓ The exoskeleton hardens

✓ The fangs darken

Only then should feeding resume.

Offering prey too soon can be dangerous.

Molting Problems

While most molts occur successfully, complications can occasionally arise.

Potential issues include:

Stuck Molts

Parts of the old exoskeleton remain attached.

Lost Limbs

A leg may become trapped during the process.

Incomplete Molts

The spider cannot fully emerge.

Many molting complications are difficult to correct safely.

The best prevention is proper husbandry before the molt begins.

Humidity and Molting

Proper hydration plays an important role in successful molts.

Healthy hydration helps:

  • Maintain flexibility

  • Support exoskeleton separation

  • Reduce molting complications

Remember:

Hydration and humidity are not the same thing.

Provide drinking opportunities while maintaining good ventilation.

Species and Molting

The molting process is similar across all jumping spider species.

Whether you're caring for:

  • Regal Jumping Spiders (Phidippus regius)

  • Bold Jumping Spiders (Phidippus audax)

  • Canopy Jumping Spiders (Phidippus otiosus)

  • Mustache Jumping Spiders (Phidippus mystaceus)

  • Shadow Jumping Spiders (Phidippus adumbratus)

  • Paraphidippus fartilis

  • Giant Malaysian Jumpers (Hyllus diardi)

the same general principles apply.

Common Beginner Mistakes

Assuming the Spider Is Sick

Premolt behavior often resembles illness.

Offering Food Repeatedly

Food refusal is normal during premolt.

Destroying the Molting Hammock

The hammock serves an important purpose.

Handling During Premolt

Avoid interaction whenever possible.

Panicking

Many keepers worry during their first molt.

In most cases, the best action is patience.

How Long Does a Molt Take?

The answer depends on age and species.

Spiderlings

Often recover quickly.

Juveniles

May spend several days hidden.

Adults

Sometimes remain inside retreats for extended periods before and after molting.

Every spider is different.

The Tiny Coven Approach

At Tiny Coven Jumpers, we view molting as one of the most fascinating moments in a spider's life.

It is a reminder that growth often happens out of sight.

The spider disappears.

It becomes still.

And then, after patience and time, it emerges transformed.

As keepers, our job is not to intervene.

Our job is to provide a safe environment and allow nature to do what it has done for millions of years.

A Keeper's Rule of Thumb

If your spider is molting, your best husbandry tool is patience.

Observe.

Provide hydration.

Maintain proper conditions.

And trust the process.

Because every successful molt is another step in your spider's journey—and another reminder of just how remarkable these tiny animals truly are.