Your sick jumping spider is not acting like itself. Maybe it is sitting on the floor of the enclosure when it normally climbs. Maybe it has not eaten in two weeks. Maybe it looks thinner than it did last week, or it is completely still and you cannot tell if it is sleeping or something is genuinely wrong. You need a starting point.
This guide is a triage checklist. Work through each section in order. By the end, you should have a likely cause, a first action, and a clear signal for when to escalate to a vet.
Key Takeaways
- Most sick jumping spider problems fall into five categories: molt-related, dehydration, husbandry error, old age, or genuine illness.
- The first step is always to rule out molt: a spider sealed inside a silk sac is almost certainly healthy and needs to be left alone.
- A shriveled abdomen points strongly to dehydration, which is often fixable at home within 48 hours.
- A spider that has not eaten for more than 3 weeks outside of a molt warrants active investigation, not just waiting.
- Legs curled tightly under the body outside of a molt context is a serious sign: contact a vet.
What does a sick jumping spider look like?
A sick jumping spider typically shows one or more of these warning signs, according to the keeper community at poramorart.ca and mypetjumpingspider.com:
- Refusing food for unusually long periods outside of pre-molt
- A shrunken, shriveled, or deflated abdomen instead of a firm, round one
- Weak or uncoordinated movements, frequent falls off the enclosure walls
- Staying on the enclosure floor instead of climbing or webbing near the top
- Jerky, twitchy motions or tremors
- Dull or faded coloration compared to normal
- Lethargy and constant hiding outside of any molt period
Jumping spiders instinctively hide weakness, so subtle changes matter. Early detection gives your spider the best chance of recovery.
Step 1: Is your spider in a molt sac?
Before anything else, look for a white or off-white silken pouch. Jumping spiders seal themselves into a silk retreat before molting, and they may remain there for several days to several weeks.
Signs you are looking at a molt sac rather than a sick spider:
- Dense white silk, often positioned in a corner or at the very top of the enclosure
- The spider is inside or attached to it and not responding to you
- Food interest dropped gradually over the days or weeks before this happened
What to do: nothing. Do not poke, open, or disturb the sac. A spider interrupted mid-molt can lose limbs or die from the interruption. Remove any live prey from the enclosure immediately. The spider will emerge on its own when it is ready.
The full jumping spider molting guide covers exactly what to expect at each stage, how long each phase takes, and when you genuinely need to worry.
Step 2: Match your spider to the symptom table
If your spider is not in a molt sac, find the closest match to what you are seeing below.
| Symptom | Most likely cause | First action |
|---|---|---|
| Shriveled or wrinkled abdomen | Dehydration | Offer a water droplet; mist one enclosure wall |
| Lethargic, sitting on enclosure floor | Dehydration or pre-molt | Check abdomen shape; look for any silk retreat |
| Refusing food for 7 to 14 days | Pre-molt or stress | Remove uneaten prey; do not force-feed |
| Refusing food for 3+ weeks with no molt | Illness, husbandry error, or old age | Review temps, humidity, enclosure size; consider vet |
| Abdomen darkening to gray or blue-black | Normal pre-molt change | Wait; do not disturb |
| Legs curled tightly under the body | Severe dehydration, illness, or dying | Attempt rehydration immediately; vet if no response in 2 hours |
| Moving in circles or erratic lurching | Neurological issue or DKS | Vet; do not attempt home treatment |
| White fluffy growth on the body | Fungal infection | Vet immediately |
| Small dark hole or spot on the abdomen | Possible parasitoid fly larvae | Vet immediately |
| Spider fell and is not recovering | Injury from drop | Reduce climbing height; quiet environment for 48 hours |
| Jerky, twitchy movements or tremors | Dyskinetic Syndrome (DKS) | Supportive care; no known cure |
Dehydration
Dehydration is the most common fixable health problem in captive jumping spiders. The key sign is a shriveled, deflated, or wrinkled abdomen. A healthy abdomen is round and noticeably plump.
How to address it:
- Place a small water droplet (3 to 4 mm) on the enclosure wall near the spider.
- Mist one corner of the enclosure lightly with room-temperature water.
- Watch for the spider to approach and drink. Mouthparts moving against the droplet surface means it is drinking.
- Do not offer food until the abdomen looks round again, usually within 24 to 48 hours.
- For moderate to severe dehydration, try the Spider ICU method: place the spider in a small container with air holes, line walls with damp paper towels, and leave the floor dry so it is not sitting in water.
Full instructions including how to tell dehydration apart from pre-molt are in the jumping spider dehydration guide.
Lethargy without a shriveled abdomen
If your spider is slow and withdrawn but the abdomen looks normal and round, the most common causes are environmental rather than illness.
Temperature too low. Jumping spiders are ectotherms. Their metabolism, digestion, and activity all slow significantly in cool conditions. The ideal range for common species such as Phidippus regius and P. audax is 22 to 28 C (72 to 82 F). Below 18 C (65 F), a spider may barely move at all. Always check temperature with a thermometer placed inside the enclosure, not on the outside of the glass.
Enclosure too large. A spider housed in a space much bigger than it needs will often spend more time hiding and moving far less. This is stress behavior, not illness. Downsizing the enclosure frequently resolves it.
Recent molt. Even after emerging from the molt sac, a freshly molted spider may spend several days eating nothing and moving minimally while its new exoskeleton hardens. This is normal for up to a week post-molt and requires no intervention.
Handling stress. A spider that was dropped, escaped, or has been handled very frequently may withdraw for several days. Give it 5 to 7 days of complete quiet and no handling before reassessing.
Heatstroke. If the enclosure was placed in direct sunlight or next to a heat source, heatstroke is possible. Move the spider to a cool, humid environment immediately. Recovery from mild heatstroke is possible; severe cases are often fatal even with intervention.
Not eating
A sick jumping spider refusing food is one of the most common keeper concerns. How long the spider has been refusing food matters more than the fact that it is refusing.
| Duration of food refusal | Most likely explanation |
|---|---|
| Up to 7 days | Pre-molt, temporary satiation, or mild stress |
| 7 to 14 days | Pre-molt (check for silk building and abdomen darkening) |
| 14 to 21 days | Pre-molt, or review husbandry (temperature, humidity, prey size) |
| 3+ weeks with no molt sign | Investigate actively: vet is appropriate at this point |
Other factors that matter: prey type, prey size, time of day when you offer food (jumping spiders are diurnal and should be fed during daylight hours), and whether live prey is being left in the enclosure unsupervised. Uneaten live prey stresses spiders and can injure them. See the full jumping spider not eating guide for a step-by-step walkthrough.
Genuine illness
True illness is less common than husbandry errors, but it does happen. Signs that point away from care problems and toward actual illness or a condition that needs veterinary input:
Dyskinetic Syndrome (DKS). A poorly understood neurological condition documented in the captive jumping spider community, particularly at mypetjumpingspider.com. Signs include jerky, twitchy movements, loss of coordination, tremors, and progressive decline. There is no known cause and no known treatment. Supportive care (consistent humidity, easy access to water, no live prey in the enclosure) is the only current option.
Parasitoid flies (Phorid flies). If you keep fruit flies as feeders, phorid flies can parasitize your spider. The first sign is often a small dark hole or spot on the abdomen, followed by rapid decline over days. This requires a vet immediately. See the fruit fly culture setup guide for how to keep your cultures clean and reduce phorid fly risk.
Fungal infections. Unusual white, gray, or black growths on the body that are not silk. A vet is needed. Do not attempt to remove anything yourself.
Nematodes. Internal roundworm parasites that can enter through wild-caught or poorly sourced feeder insects. Signs include dramatic progressive weight loss and lethargy despite what looks like adequate hydration. A vet is required.
Neurological symptoms from external causes. Circling, falling repeatedly, inability to control limb movement. These can follow a bad molt, pesticide exposure, or a feeder insect that injured the spider in the wrong place. A vet is required.
If you suspect any of these, the why did my jumping spider die guide covers parasites and toxic exposure in more detail, including guidance on finding an exotic vet who treats invertebrates.
Husbandry checklist
Before concluding genuine illness, work through this list. Most spiders described as sick are actually responding to something fixable in their environment.
- Temperature: 22 to 28 C inside the enclosure. Measure it; do not estimate based on room temperature.
- Humidity: One moist surface present at all times. Mist every 1 to 3 days depending on climate and how quickly your enclosure dries.
- Enclosure size: Roughly 3 times the spider’s body length on each dimension as a minimum. Larger can cause stress.
- Ventilation: Cross-ventilation from two sides prevents mold and stagnant air. Stagnant air stresses respiration.
- Lighting: 12 hours of light per day minimum. Jumping spiders are diurnal hunters and need light cycles to behave normally and eat.
- Prey size: No prey item larger than half the spider’s body length. Oversized prey causes stress and potential injury.
- Prey type: A varied diet is better than a single prey type. Dubia roaches, bottle flies, crickets, and mealworms each offer different nutritional profiles. A spider refusing one may take another.
- Wild-caught feeders: Avoid them entirely, or gut-load carefully and quarantine. Wild-caught feeders can carry pesticides, parasites, and unknown pathogens.
For full enclosure specifications, see the jumping spider enclosure setup guide and the complete jumping spider care guide.
When to contact a vet
Reach out to an exotic vet who sees invertebrates if any of the following apply:
- Legs are curled under the body and the spider does not respond to gentle stimulus after 2 hours of rehydration attempts.
- You see any growth, hole, or unexplained discoloration on the exoskeleton.
- The spider is moving in circles or has lost coordinated limb movement.
- Food refusal has lasted more than 3 weeks with no evidence of a pending molt.
- You suspect pesticide or chemical exposure: recently used aerosols nearby, plug-in air fresheners, treated houseplants brought into the room, flea treatments on other pets in the household.
Finding an exotic vet in advance is worth doing before an emergency arises. Ask in jumping spider keeper communities online. Most active communities maintain pinned vet lists by region or country.
Not every sick jumping spider can be saved, and not every problem has a home remedy. But the large majority of what looks like illness turns out to be dehydration, a pending molt, a temperature problem, or a husbandry issue. All of those are fixable today. Start with the symptom table, make one change at a time, and give your spider 24 to 48 hours to respond before drawing any conclusions.