How To Care For Terrestrial Tarantula Spiderlings

Terrestrial tarantula spiderlings are simultaneously some of the most rewarding animals to raise and some of the easiest to kill through well-meaning mistakes. The gap between what a terrestrial tarantula spiderling needs and what a new keeper assumes it needs is wide enough to cause real problems, which is why getting the fundamentals right before a sling arrives matters more than it does with almost any other pet. The good news is that once you understand what these tiny spiders actually require, caring for terrestrial tarantula spiderlings becomes genuinely straightforward.

What Exactly Is A Terrestrial Tarantula Spiderling?

A spiderling — almost always shortened to sling in the hobby — is simply a juvenile tarantula in its earliest stages of life, typically anywhere from freshly hatched at a few millimetres up to around an inch in legspan. Terrestrial species are ground-dwelling tarantulas that burrow into soil rather than climbing trees or webbing high up in vegetation, and that lifestyle distinction shapes everything about how they should be housed. The species most commonly available as slings in the hobby — the Brazilian White Knee, Arizona Blonde, Texas Brown, Honduran Curly Hair, Chilean Rose Hair, and dozens of others — all spend their lives on or in the ground, and their sling care reflects that.

Choosing The Right Enclosure For Terrestrial Tarantula Spiderlings

The single most common enclosure mistake with terrestrial tarantula spiderlings is housing them in too large a space. A sling that measures a centimetre across has no business living in an adult-sized enclosure, and the reason is not just aesthetic — a tiny sling in a large enclosure struggles to find food, has difficulty managing the humidity gradient it needs, and can desiccate before it ever crosses paths with a prey item. The enclosure for a terrestrial tarantula spiderling should feel snug but not cramped, with floor space roughly four times the spider’s diagonal legspan in any direction. For a very young sling at half a centimetre, that means something the size of a film canister or a small deli cup is entirely appropriate and genuinely better than anything larger.

Paladin Exotics’ care guide recommends basing enclosure size on the diagonal legspan, with terrestrial species needing floor space approximately four times that measurement. Most keepers start slings in small deli cup containers or dedicated sling enclosures and size up every couple of moults as the spider grows. Height above the substrate should always be kept minimal for terrestrial slings — a heavy spider falling from even a few centimetres can rupture its abdomen, and the risk only increases as the spider grows. Our best tarantula sling enclosure guide covers the specific containers and dedicated sling setups that work best at every size stage.

Substrate Depth And Composition For Terrestrial Slings

If there is one thing that separates experienced sling keepers from beginners, it is understanding how important deep substrate is. Terrestrial tarantula spiderlings are obligate burrowers in most species, and a sling that cannot burrow is a stressed sling. The enclosure should be filled with substrate to approximately two-thirds full, which leaves just enough headroom above the surface while ensuring the spider can excavate a tunnel of meaningful depth relative to its body size. For a 0.5cm sling, even 3 centimetres of substrate represents a significant burrow — the depth ratio matters more than the absolute measurement.

Coconut coir is the most widely used substrate for terrestrial tarantula spiderlings and it earns that status honestly — it holds burrow structure, retains moisture without becoming waterlogged easily, does not compact to concrete when dry, and is safe if accidentally ingested. A blend of coconut coir and peat moss works well for species that need slightly more moisture retention. The Tarantula Collective recommends filling sling enclosures at least two-thirds with substrate, and The Spider Shop notes that three to four inches represents the practical minimum for most terrestrial species. Avoid potting soil with added fertilisers, perlite, or any substrate containing cedar or pine, all of which carry compounds toxic to tarantulas.

Moisture And Humidity For Terrestrial Tarantula Spiderlings

Here is the critical point that surprises most new keepers: terrestrial tarantula spiderlings need more moisture than adults of the same species, regardless of whether that species is typically kept dry or humid as an adult. The reason is physiological — a sling has a vastly higher surface area to volume ratio than an adult, which means it loses moisture to the environment much faster. A desert-adapted species like the Arizona Blonde is kept dry as an adult, but its slings still need a slightly damp section of substrate or they will desiccate and die. Paladin Exotics confirms this explicitly: regardless of the adult’s needs, slings of almost all species require slightly higher humidity because they desiccate so much faster.

The practical approach is a moisture gradient rather than uniform dampness throughout the substrate. Dampen one corner of the enclosure or the lower portion of the substrate while leaving the upper portion and the opposite side dry. This gives the sling the ability to position itself exactly where its needs are being met — burrowing toward moisture when dehydrated and moving toward the drier surface when it wants to feed or moult. A very small, shallow water bottle cap on the surface can provide additional moisture access for slings above roughly 2 centimetres in legspan, though anything smaller risks the sling drowning in even a few millimetres of water.

Feeding Terrestrial Tarantula Spiderlings

Prey size is the most important variable in sling feeding, and the rule is simple: nothing larger than the sling’s abdomen. A prey item that is too large will ignore the spider at best and injure it at worst, and even crickets left to wander overnight in an enclosure with a sling that has just moulted can be fatal. Very small slings — under roughly a centimetre — are best fed pre-killed or crushed prey items placed directly at the burrow entrance, since they often cannot locate or overpower live prey of any practical size. Fruit flies work well for the tiniest slings, transitioning to pinhead crickets as the spider grows and then to small roach nymphs or appropriately sized crickets as it approaches the juvenile stage.

Feeding frequency for terrestrial tarantula spiderlings should be every two to three days for the smallest individuals, dropping to every five to seven days as the sling grows toward the juvenile stage. The Tarantula Collective recommends feeding slings every two to three days with appropriately sized prey, and the reasoning behind the frequency is that a fast growth rate requires consistent caloric input. Always remove uneaten prey within 24 hours. A sling that refuses food for a week or two is almost certainly approaching a moult, which brings us to the most important event in a sling’s early life.

Understanding The Moulting Process In Terrestrial Tarantula Spiderlings

Moulting is how tarantulas grow — by shedding their entire exoskeleton and expanding before the new one hardens. For spiderlings this happens frequently, sometimes every few weeks for very small individuals growing quickly under good conditions. The signs of an impending moult in a terrestrial tarantula spiderling include refusing food, sealing the burrow entrance with silk and soil, and in some species flipping onto their back and lying motionless — the position from which they actually shed the old exoskeleton. A sling lying on its back is not dying, and The Spider Shop is emphatic about this: if your spider is moulting, leave it completely alone.

The golden rule during moulting is zero interference. Do not add water, do not add food, do not disturb the enclosure, and do not attempt to help even if the moult appears to be taking a long time. A moulting tarantula’s new exoskeleton is soft, its fangs are white and useless, and any interference during this period can permanently injure or kill the spider. After the moult is complete, wait at least a week before offering food again — longer for larger individuals — to allow the new exoskeleton and fangs to fully harden. The slight increase in ambient humidity that The Spider Shop recommends during the moulting process can be achieved simply by dampening the substrate corner slightly before a moult is anticipated.

Temperature Requirements For Terrestrial Tarantula Spiderlings

Most terrestrial tarantula spiderlings from tropical species thrive at room temperature in the range of 72 to 82°F, with species from more temperate or high-elevation habitats preferring the cooler end of that range. The general guidance from experienced sources is that the growth rate of a sling is directly tied to temperature — warmer conditions within the species-appropriate range produce faster growth and more frequent moults. This means a keeper who wants to grow slings out quickly will maintain slightly warmer temperatures, while a keeper prioritising longevity and naturalistic conditions will keep things at the lower end of the species-appropriate range. Our best tarantula thermometer guide covers temperature monitoring options appropriate for small sling enclosures where ambient room readings may not accurately reflect conditions inside the container.

Common Mistakes When Caring For Terrestrial Tarantula Spiderlings

The mistakes that kill slings most consistently are the same ones that get repeated across the hobby constantly. Oversized enclosures, undersized substrate depth, prey that is too large, and interference during moulting account for the vast majority of avoidable sling deaths. A close second is providing too much water to the wrong species — flooding the substrate of a desert Aphonopelma sling because the keeper read that slings need humidity without understanding the moisture gradient concept. Our tarantula dehydration article covers identifying and correcting the opposite problem, which is equally real.

The other mistake worth specifically flagging is checking on the sling too frequently when it has sealed its burrow. A sling that has plugged its entrance and gone quiet is almost certainly pre-moult, and the instinct to excavate the burrow to see if the spider is still alive is one of the most dangerous things a keeper can do. Patience is the skill that separates successful sling keepers from frustrated ones, and a sling that has not been seen for two weeks inside a sealed burrow is almost certainly doing exactly what it is supposed to be doing.

When To Transition To A Larger Enclosure

A terrestrial tarantula spiderling should be rehoused when it has used approximately two-thirds of the available floor space, or when its legspan reaches around one-quarter of the enclosure’s floor dimension. Rehousing too frequently is stressful for the spider, so the goal is to move into an enclosure that will comfortably last two or three moults rather than one that fits exactly right at the moment of transfer. Rehousing is best done a week or more after a moult when the spider is fully hardened and at its most robust, and using a cup-and-card technique to move the sling without direct contact reduces stress for both the spider and the keeper. Our best tarantula enclosure guide covers the progression of enclosure sizes from sling through juvenile to adult for terrestrial species. Everything you need to raise a terrestrial tarantula spiderling correctly from day one is covered on our best tarantula products page.