Updated: May 26, 2020
Jumping spider sling care: Did your wildcaught jumping spider mama lay an egg sac? Or did you breed some of these little delights and are now wondering how to best take care of the spiderlings? Through much trial and error, here is the method I've developed that I have had the most success with.
Jumping spiders will sit on their clutch for about 2-3 weeks before the eggs hatch, depending on temperature. Upon hatching, the slings (spiderlings) will remain in the sac until they molt once more, and emerge as 2nd instar slings. (The first molt is the shedding of the egg membrane and not their exoskeleton as we define molting from there on out). This takes about 2 weeks, depending on temperature etc.
Food for slings:
While you're waiting for them to emerge, obtain a culture or two of melanogaster fruit flies (flightless or wingless preferably). These take some time to start producing, and it's advised that you see larval development before feeding off the flies. This will sustain them until they are big enough to take other prey items. The rule of thumb is, they will take down prey about their size. Prey items such as crickets and mealworms need to be fed with supervision, as they can munch on and do damage to molting spiders. In another molt or two, they can start eating hydei fruit flies (next size up).
Removing slings into new housing: This is done by carefully detaching the nest with a cotton swab, or if the nest was built in a way that it can be removed easily as a whole, then gently nudge the nest to encourage mom to come out before removing it. Sometimes I have the moms lay eggs in a sling-proof container to begin with, then I just remove the mom. If you need to move individual slings, use a soft paintbrush, or makeup brush, and gently swipe from behind their bums in a slightly upwards motion. This will make them attach to the brush with their silk draglines, allowing you to dangle and move them wherever you need to.
Housing for slings: The pictures show my set up for the slings after removing the sac from mom. I prop them up on some Spanish Moss, or some tulle ribbon, with paper towel or substrate such as coco fiber on the bottom that can retain moisture. The lid of the container needs to be well vented. This allows for evaporation of added moisture on the bottom without the water gathering on the sides and drowning the slings, while providing enough humidity for molting and access to water. I would someday like to experiment with a tiny bottle cap of water with grave in it to see if that works well for drinking water, like many do in the Tarantula hobby. But for now, this is the consensus most have arrived at for the best way of providing water.
There is a door on the side that I've cut out and put back in place with tape. Since the slings like to nest up top, this door on the side allows me to water and add fruit flies via a funnel without risking a bunch of slings escaping. This little trick I learned from http://www.mypetjumpingspider.com/spiderlings/. And it has not failed me yet! I also label the cups on the tape of the slings hatch month and species. If you don't wish to prepare your own vented lids, you can purchase these 32oz deli cups with mesh cloth lids from Rainbow Mealworms and Mantisplace, etc.
They can be house communally until they are about the size to eat house flies. At which point, I'd separate them into individual enclosures.
Responsible breeding: Before you breed, make sure you are prepared for 300+ slings. If they are a non native species, that's the amount of slings you'll have to find homes for, keep caring for, or cull. If you find that one sac is enough, you can freeze subsequent sacs as soon as they are laid before disposing of them. Otherwise, you can reach out to see if anyone else might take on the slings and send them off right after they hatch. However, make sure whoever you send the slings is trustworthy and ethical in terms of keeping non native species confined and finding them new homes.
Hopefully this helps a bit on early sling care!
More Photos of Sling Set-Ups: