Choosing the Right Feeder Size for Jumping Spiders

Choosing the right feeder is not just about what species your jumping spider will eat.

Size matters.

A feeder that is too large can intimidate or injure a spider. A feeder that is too small may not provide enough nutrition or may simply fail to trigger a feeding response.

The goal is to choose prey that is appropriately sized, active enough to get the spider’s attention, and manageable for the spider to subdue safely.

A Simple Size Rule

A good general rule is to offer prey that is about the same size as the spider’s abdomen or smaller.

For many jumping spiders, prey around one-half to roughly the full size of the spider’s body can work well depending on the species, age, confidence, and prey type.

There is no single perfect ratio for every spider.

A bold adult jumper may confidently take prey near its own size, while a young or timid spider may do better with something much smaller.

Start Smaller When You Are Unsure

If you are deciding between two feeder sizes, the smaller option is usually the safer starting point.

You can always move up later.

Oversized prey can:

• Stress the spider
• Cause the spider to retreat instead of hunt
• Make feeding more difficult
• Increase the chance of injury
• Be especially risky during premolt or immediately after a molt

Young spiders in particular benefit from appropriately small prey.

Feeder Size by Spider Stage

Slings

Very young jumping spiders need very small prey.

Common options include:

• Flightless fruit flies
• Very small larvae
• Other tiny feeders appropriate to the spider’s size

For very small slings, Drosophila melanogaster is often a practical choice because of its smaller adult size.

Juveniles

As a spider grows, you can gradually increase feeder size.

Juveniles may take:

• Larger fruit flies
• Small mealworms
• Small fly larvae
• Small adult flies
• Other appropriately sized feeders

This is often the stage where Drosophila hydei becomes useful because it is larger than D. melanogaster.

Subadults and Adults

Larger jumping spiders can handle a broader range of feeders, including:

• House flies
• Blue Bottle Flies
• Appropriately sized mealworms
• Larger fruit flies
• Other active insect prey

Adult flying prey can be particularly effective because the movement tends to stimulate natural hunting behavior.

D. melanogaster vs. D. hydei

Fruit flies are among the easiest feeders to size appropriately.

Drosophila melanogaster

D. melanogaster is the smaller of the two commonly cultured feeder fruit flies.

It is generally better suited for:

• Small slings
• Very young juveniles
• Small jumping spider species
• Animals that need tiny prey

Drosophila hydei

D. hydei is larger.

It is often better suited for:

• Larger slings
• Juveniles
• Smaller adult jumpers
• Spiders that have outgrown D. melanogaster but are not ready for larger flies

If your spider consistently ignores melanogaster but is still too small for house flies, hydei can be a useful middle step.

House Flies

House flies are an excellent feeder for many juvenile and adult jumping spiders.

They provide:

• Strong movement
• Flying prey behavior
• Natural hunting stimulation
• A larger meal than fruit flies

For spiders that are large enough to handle them, house flies can be one of the most effective feeders for triggering a hunting response.

Blue Bottle Flies

Blue Bottle Flies are larger than house flies.

They are best suited for:

• Larger juvenile jumpers
• Subadults
• Adults
• Larger species that can confidently subdue flying prey

Because Blue Bottle Flies are strong fliers and relatively large, they may be too much for a small or timid spider.

If you are unsure, start with a house fly or smaller feeder first.

Mealworms

Mealworms are useful because they come in a range of sizes.

They can work well for:

• Juveniles
• Subadults
• Adults

Choose a mealworm that the spider can comfortably overpower.

Do not leave a mealworm unattended in an enclosure for long periods, especially if the spider is not interested in feeding.

Mealworms can burrow into substrate and may become difficult to retrieve.

Micro, Mini, Medium, and Large Mealworms

Size labels are useful, but the actual feeder size matters more than the name.

A “medium” mealworm may be appropriate for one jumping spider and far too large for another.

Use the spider itself as your reference.

If the mealworm appears substantially larger or more powerful than the spider, choose a smaller one.

Fly Pupae Are Not the Feeding Stage

Blue Bottle Fly pupae and House Fly pupae are sold primarily so customers can hatch them into adult flies.

The pupa itself is not the same feeding experience as an active adult fly.

For spiders that strongly prefer moving aerial prey, hatch the pupae first and offer the adult fly.

Movement Matters as Much as Size

Jumping spiders are visual predators.

The way a feeder moves can strongly affect whether the spider recognizes it as prey.

A spider may ignore a slow or stationary feeder while immediately reacting to a fly.

This is why a spider that refuses mealworms may still enthusiastically take:

• Fruit flies
• House flies
• Blue Bottle Flies

It does not necessarily mean the spider is not hungry.

It may simply prefer a different prey type.

Watch the Spider’s Reaction

The spider will often tell you whether the feeder is appropriate.

Positive hunting behavior can include:

• Turning toward the feeder
• Tracking it visually
• Stalking
• Approaching
• Pouncing

Signs the feeder may be too intimidating include:

• Retreating
• Running away
• Hiding
• Repeatedly avoiding the prey
• Defensive posturing

If the spider appears intimidated, remove the feeder and try something smaller.

Do Not Force a Larger Feeder

There is no benefit to pushing a spider to take the largest prey possible.

A smaller feeder that the spider confidently captures is usually preferable to oversized prey that causes stress.

You can offer more than one appropriately sized feeder if additional food is needed.

Be Extra Careful Around Molting

Jumping spiders are particularly vulnerable during premolt, molting, and immediately afterward.

A spider preparing to molt may refuse food.

Do not assume that means you need to offer larger or more stimulating prey.

Uneaten live feeders can become a problem during this vulnerable period.

Remove prey if the spider is not interested.

Abdomen Size Can Help Guide Feeding

The spider’s abdomen can provide useful context.

A very plump abdomen may indicate the spider does not currently need a large meal.

A noticeably smaller abdomen may suggest the spider is ready to feed.

Feeder size and feeding frequency should be considered together rather than independently.

Variety Is Useful

No single feeder has to be the only food source.

A rotation might include:

• Fruit flies for smaller meals
• House flies for active hunting
• Blue Bottle Flies for larger adult prey
• Mealworms for variety
• Other appropriately sized feeders

Offering variety can provide different movement patterns and feeding experiences.

Quick Feeder Size Guide

This is a starting point, not a rigid rule.

Individual spiders vary.

When in Doubt, Go Smaller

The easiest rule to remember is:

A slightly undersized feeder is usually safer than an oversized one.

Watch how your spider responds and adjust from there.

As your spider grows and becomes more confident, you can gradually increase feeder size.

The Bottom Line

The best feeder is one your jumping spider can safely recognize, stalk, and capture.

Consider:

• Spider size
• Spider age
• Feeder size
• Feeder movement
• Hunting confidence
• Whether the spider is approaching a molt

Start conservatively, observe the spider’s behavior, and increase prey size as the spider grows.

A well-sized feeder makes hunting safer, easier, and more natural.