A jumping spider egg sac is a small, flattened pouch made of dense white or off-white silk, usually tucked inside a silken retreat the female builds in a sheltered spot. If you’ve found one in your home or your pet jumping spider just produced one, here’s what to expect and how to handle it.
What an Egg Sac Looks Like
Jumping spider egg sacs look different from the round, ball-shaped sacs you might associate with other spiders. They’re typically lens-shaped or slightly flattened, wrapped in tightly woven silk that appears opaque and papery. The sac itself is usually white to cream-colored and relatively small, often no bigger than your pinky fingernail depending on the species. You’ll almost always find it inside a thicker silk nest or retreat, since females don’t leave egg sacs out in the open. Common hiding spots include corners of window frames, under bark, inside rolled leaves, or tucked behind objects on shelves.
Incubation Time and Temperature
Eggs generally hatch within one to four weeks, with temperature being the biggest factor in how quickly development happens. Warmer conditions speed things up, while cooler environments slow them down. For regal jumping spiders, one of the most popular pet species, eggs typically hatch in about two to three weeks when kept at 75 to 80°F. Bold jumping spiders, another common species found across North America, tend to take closer to a full month at room temperature.
The babies don’t leave the sac right away after hatching. During the first stage of life, spiderlings stay inside the sac, complete their first molt, and then begin to disperse. So even after hatching occurs, you may not see any activity for several more days until tiny spiderlings start emerging from the silk.
How the Mother Behaves
Once a female jumping spider produces an egg sac, she guards it closely. She’ll stay inside or very near her silk retreat, and she typically stops hunting during this period. This fasting and guarding phase is completely normal. The most important thing, whether this is a pet spider or one you’ve found in your home, is to leave her alone. Stressed mothers have been known to eat their own egg sacs, so avoid disturbing the area, moving the enclosure, or trying to inspect the sac up close.
Caring for an Egg Sac in Captivity
If your pet jumping spider has laid an egg sac, care comes down to three things: minimal disturbance, stable humidity, and patience. Keep humidity around 60 to 80% by lightly misting one corner of the enclosure every two to three days. Avoid spraying the sac directly, because wet silk promotes mold growth, which is one of the biggest threats to developing eggs. Good ventilation in the enclosure helps prevent this.
Maintain temperatures between 75°F and 85°F (24°C to 29°C). Keep the enclosure in a calm location away from vibrations, direct sunlight, and foot traffic. Resist the urge to open the enclosure to check on progress. You’ll know hatching has been successful when you start seeing tiny spiderlings emerging from the retreat.
Once Spiderlings Emerge
When spiderlings start leaving the sac, they’re ready to be separated and cared for individually. Jumping spiders can be cannibalistic, so separating them relatively quickly matters. A single egg sac can produce dozens of babies, which is a lot of tiny spiders to manage. If you weren’t expecting this or aren’t prepared to raise that many, reaching out to a jumping spider breeder is your best option. Breeders regularly help rehome unexpected clutches and can take them off your hands.
Finding an Egg Sac in Your Home
If you’ve found a jumping spider egg sac indoors and you’re not keeping the spider as a pet, you have a few options. The simplest approach is to leave it alone if it’s in an out-of-the-way spot. Jumping spiders are harmless to people and are effective pest controllers. The mother will guard the sac for a few weeks, the babies will emerge and disperse on their own, and most will find their way to small crevices around your home or outside.
If you’d prefer to relocate the sac, wait until the mother has moved away from it, then gently scoop the entire silk retreat (sac included) onto a piece of paper or cardboard and move it to a sheltered outdoor spot like a garden shed, under a porch railing, or inside a crack in a fence. Avoid separating the sac from the retreat if possible, and try not to compress or squeeze the silk. If the mother is still actively guarding, it’s better to wait. Disturbing her increases the chance she’ll destroy the sac herself.