Can a Spiderling Enclosure be too Big?

One of the most common questions that new keepers ask relates to what size enclosure a tarantula spiderling needs. Is it possible to give them too big or too small of a container?

A spiderling enclosure can be too big in the sense that the extra space makes it difficult for the sling to find food and water easily. Some keepers anecdotally have found over the course of breeding that keeping slings in bigger than necessary containers slows their growth down compared to siblings that are kept in smaller spaces. Although a large enclosure won’t directly kill a spiderling, it will make it harder for the keeper to maintain proper husbandry.

That being said, sometimes it is recommended to house fast species or spiders with more potent venom in a larger sling enclosure to reduce the frequency that the keeper interacts with the specimen.

What’s the ideal size enclosure for a spiderling?

It’s common for people new to the hobby to think that the small enclosures that we keep our spiders in are cruel because they relate keeping arachnids in confined spaces to keeping dogs, cats, and birds in tiny cages.

However, spiders rarely utilize more than a few inches of their cage outside of their web or burrow because they just sit in place waiting for food to come by. They don’t need extra space to play or exercise.

Once they settle down from being moved into a new enclosure they won’t do much roaming unless something is wrong with their setup or they turn out to be a mature male.

Most spiderlings will do well in a container the size of a 20-dram to a 40-dram vial. A 20-dram vial would be appropriate for really tiny babies. A 40-dram vial has an inside height of 3-5/16” and an inside diameter (width) of 1-7/8″, while a 20-dram vial has an inside height of 2-11/16″ and an inside diameter of 1-1/2″.

As a general rule of thumb, a basic arboreal spiderling enclosure will have more height than width. A terrestrial sling setup is typically the opposite having more width than height.

However, you can set up the exact same type of container as both an arboreal and a terrestrial enclosure by varying the amount of substrate that you use.

Can an enclosure be too small for a tarantula sling?

A container can be too small for a spiderling in the sense that there isn’t enough room to put an appropriate hide or enough substrate for burrowing if the species requires it.

Maintaining moist substrate is very difficult if there’s only a thin layer. The spider should have adequate room to turn around in the enclosure that you choose, and it needs to have room for a piece of cork bark (or something similar) so that the baby feels secure.

Why don’t keepers put spiderlings in larger enclosures?

Slings kept in big containers tend to hide more and have a less aggressive feeding response. Both of these things can hinder their growth. It’s also harder for the keeper to make sure that the sling is eating if the spider doesn’t take the food immediately.

A large container for a small spider will make it more difficult to find the specimen to check up on it after a molt, and it can also make maintaining soil moisture for the sling harder than necessary. Finding a piece of cork bark that fits a larger enclosure while also making the sling feel secure can also be hard to do.

Many enthusiasts keep a large number of tarantulas in their collection and housing each one in a larger than necessary enclosure would be space prohibitive without any extra benefit to the spider.

Is there a benefit to using a slightly larger enclosure for a tarantula sling?

Sometimes a larger than usual enclosure is desirable for a sling. For example, I often keep fast species (like P. irminia) and Old World species in slightly larger sling enclosures to reduce the frequency of rehousing them so that I can minimize the risk of the spider escaping or biting me.

If you choose to do this, then make sure that the ventilation holes in the enclosure are small enough to prevent the spider from going through them.

What kind of containers work best for spiderlings?

There are a variety of small Amac boxes that work perfectly for slings 1” and under, as do Thornton Plastics snap cap vials.

The two sizes of vials that I’ve consistently used over the years are 20 drams and 40 drams. I use both the M-Series (the containers with the extra height from the lid) and the flat top packaging from Amac for raising slings.

Avoid using Kritter Keepers and similar containers with slots for ventilation for spiderlings because they can and will squeeze through these openings.

As a general rule, if the spider’s carapace can go through an opening, then so can the rest of the spider. The abdomen can squeeze through very tiny places, which is why you judge an opening based on the nonflexible carapace.

How do you make the right size ventilation holes for a spiderling?

The easiest method that I’ve found to make ventilation holes is to drill them with a tiny bit or use a flex shaft with a tiny ball bur. A 0.8mm-1mm bur for making jewelry is one of my go-to tools.

Make sure you’re using a tool that has variable speeds so that you can control how fast you’re drilling. Plastic should be drilled slowly, and the debris should be cleared from the bit frequently.

If you try to go quickly, then the plastic will just melt and get stuck on the bit (you’ll have to cut it away). One method that I like using to get uniform holes on my enclosures is to make a printable dot grid that I can tape to the plastic so I know where to drill.

Another common method that keepers use is melting holes in the plastic with a hot pin or the tip of a soldering iron. I don’t like how this type of hole looks because I prefer to keep my enclosures aesthetically pleasing.

That being said, it still works perfectly fine to create airflow. Just make sure you aren’t using a pin with a large diameter for spiderlings. Always work with proper ventilation if you are going to melt plastic.

Can a spiderling escape from the ventilation holes?

Tarantulas in general are escape artists, especially as tiny slings. If you drill the ventilation holes so that they are a larger size than the spider’s carapace, then the sling will squeeze out of the container.

If you accidentally drilled a hole too large, and you don’t have a spare container on hand, then you can plug the hole up with a hot glue gun temporarily.

How do you make sure a spiderling is eating in a big enclosure?

In my opinion, the best way to make sure that a spiderling is getting a chance to eat regardless of the enclosure size is to offer it pre-killed prey items. The food can be dropped on their cork bark (for arboreals) or outside of their burrow entrance (for terrestrials). You can also create a feeding ledge using small acrylic tiles and magnets for arboreal slings.

Final Thoughts on Enclosures for Spiderlings

There are tons of cheap plastic containers that make excellent houses for tarantula slings. As long as the container you’ve chosen is secure and see-through, don’t worry about getting anything fancy or super nice looking if you don’t have the funds to do so. Spiderlings do not need a lot of space, and they will be changing containers multiple times as they grow.