You have a jumping spider and you want to know if it is male or female. Maybe you are planning to breed. Maybe you bought what a breeder called a “female” and now you are not so sure. Maybe you are just curious. Either way, this guide gives you two reliable methods, explains exactly which one works at which life stage, and corrects a widespread mistake that causes keepers to misidentify their spiders for months.
Key Takeaways
- Two reliable methods: epigyne (underside of abdomen) and pedipalp shape (front appendages)
- The epigyne method works from roughly the fourth instar onward
- The pedipalp method becomes clear at subadult and adult stage
- Do not use color, size, or abdominal segment counting for juveniles
- Male P. regius have blue-green chelicerae (fangs); females typically have pink-purple ones at adulthood
How to Tell if a Jumping Spider Is Male or Female
The most reliable way to sex a jumping spider is to look at the underside of the abdomen. In females, the epigyne (a small, hard, dark structure between the book lungs) is visible as a defined black spot or shiny oval. Males have no epigyne. From subadult stage onward, male pedipalps develop a large bulbous tip called the palpal bulb, which looks like a boxing glove. Females have slender, simple pedipalps throughout their life. Use the epigyne for juveniles and the pedipalp shape for subadults and adults.
Why Knowing the Sex Matters
Knowing your spider’s sex is practically important, not just a curiosity:
- Males and females have very different lifespans. Males typically live 1 to 1.5 years; females 2 to 3 years.
- Males often stop eating for weeks around sexual maturity. Knowing the sex prevents unnecessary alarm.
- If you keep multiple jumping spiders, housing two together requires knowing sexes to avoid accidental pairing or injury.
- Breeding attempts require confirmed sexes in advance (see how to breed jumping spiders).
For a full lifespan comparison by sex, see jumping spider lifespan.
Method 1: The Epigyne (Works from L4 Onward)
The epigyne is the female reproductive organ. It sits on the underside of the abdomen, between the book lungs (the pale oval patches near the front of the belly). In females past the fourth instar, the epigyne is visible as a small, hard, shiny dark spot or defined oval.
Males have no epigyne. That region of the underside is smooth and undifferentiated.
How to use this method:
- Place the spider in a clear deli cup or plastic container
- Flip the container upside down while the spider walks on the inside of the lid
- Look at the underside of the abdomen with a magnifying glass or phone camera in macro mode
- Focus on the area between the two pale book lungs near the front edge of the abdomen
- A visible, shiny, hard-looking dark spot or oval structure: female. Smooth, uniform surface: male.
This method works from around the fourth instar (L4) onward. Before L4, the structures are too small to distinguish reliably even with magnification.
Method 2: Pedipalp Shape (Works at Subadult and Adult Stage)
Pedipalps are the small, leg-like appendages at the front of a jumping spider’s head. They are used for sensing and manipulating prey.
At sexual maturity:
- Male pedipalps develop a large, bulbous structure at the tip called the palpal bulb. This looks distinctly like a boxing glove or round knob. It stores and transfers sperm during mating.
- Female pedipalps remain slender and simple throughout the spider’s life.
This is the easiest method to use because you can observe pedipalps from the front without flipping the spider. On an adult Phidippus regius, the male’s palpal bulbs are clearly visible to the naked eye. For smaller species, a magnifying lens helps.
The pedipalp method is not useful for juveniles before the penultimate (second-to-last) molt. For younger spiders, use the epigyne method.
The Myth: Counting Abdominal Segments
You may have read online that females have 6 visible abdominal segments and males have 8. This count is not a reliable field method. It requires the spider to be held still in a precise orientation with clearly defined segments, which is rarely achievable without stressing the animal or using a microscope. Many keepers have misidentified their spiders for weeks or months this way.
Stick to the epigyne and pedipalp methods. They are accurate, faster, and require nothing beyond a phone camera or magnifying glass.
Method Reliability by Life Stage
| Life Stage | Approx. Size | Epigyne | Pedipalps | Best Method |
|---|---|---|---|---|
| L1 to L3 (early sling) | 1 to 3 mm | Not visible | Not differentiated | Too early to sex reliably |
| L4 to L5 (late sling) | 3 to 5 mm | Visible with magnification | Not differentiated | Epigyne (magnified) |
| L6 to L7 (juvenile) | 5 to 10 mm | Clearly visible | Starting to differentiate in males | Either; epigyne more reliable |
| Subadult | 10 to 15 mm | Clearly visible | Palpal bulb forming in males | Both; pedipalp increasingly clear |
| Adult | 15 to 22 mm (P. regius) | Clearly visible | Fully developed in males | Both; pedipalp is fastest |
What Male and Female Phidippus Regius Look Like Overall
Beyond the anatomical methods, adult P. regius show visible differences that become reliable at adulthood only:
Female P. regius:
- Larger and heavier, especially in the abdomen
- Orange, tan, gray, or white banded abdomen are common color forms
- Chelicerae (fangs) typically appear pink to purple
Male P. regius:
- Smaller and more slender overall, particularly in the abdomen
- Iridescent blue-green chelicerae are a strong male indicator in this species
- White facial tufts (orbital tufts) are typically more prominent
- More dramatic face patterning overall
Do not use color or size alone to sex juveniles of any jumping spider species. Color forms vary within species, and juveniles of both sexes look very similar until the penultimate or final molt.
Chelicerae Color: Useful for P. regius, Unreliable for Other Species
The chelicerae (fang) color rule applies most clearly to Phidippus regius:
- Blue-green fangs: almost certainly male
- Pink to purple fangs: almost certainly female
For Phidippus audax (the bold jumping spider) and most other salticid species, chelicerae color is not a reliable sexing indicator. Both sexes can display similar fang coloration. Stick to the epigyne and pedipalp methods for any species other than P. regius (see the Phidippus audax care guide for species-specific notes).
Before You Buy: Asking a Seller for the Sex
If you are buying from a store or breeder and want a specific sex:
- Request a subadult or adult spider, not a juvenile. Sexing juveniles accurately requires skill and equipment most sellers do not apply.
- Ask for a photo of the underside (for epigyne) or a front-facing photo showing pedipalps.
- A breeder selling “female guaranteed” should be selling subadult or adult animals, not L4 through L6 juveniles.
- Be skeptical of any guarantee based on color alone for juvenile specimens.
Frequently Asked Questions
Can I sex a jumping spider as a sling? Not reliably at L1 through L3. From L4 onward, the epigyne method with a magnifying glass or macro camera works with patience. Most keepers wait until L6 or subadult stage for a confident call.
My jumping spider looks female but the pedipalps seem thick. What does that mean? Female pedipalps can appear relatively thick in some individuals, but they will not develop the distinct round bulb that males display. If you are unsure, check the underside for the epigyne. If it is present, the spider is female.
I’ve had my spider for months and still can’t tell. What should I do? Wait for the next molt. Each molt makes the anatomical differences more pronounced. If your spider is still at L5 or below, the pedipalp method simply has not become reliable yet.
Once you have confirmed you have a mated female and you are watching for an egg sac, the next step is jumping spider egg sac care. For general care at any life stage, the jumping spider care guide is the starting point.
Sexing a jumping spider gets fast once you know what you are looking at. The first time you flip a deli cup and spot the epigyne clearly, you will wonder how you ever second-guessed it.