The Best (& Worst) Terrarium Insects and Bugs: 12+ Species

Today, we’re talking about terrarium bugs. The good, the bad, and the ugly.

Love them or hate them, insects and bugs can make a valuable addition to a terrarium ecosystem.

Of course, that’s provided you get the right ones.

Some can help keep your terrarium clean, rich in nutrients, and free of pests. Whereas others simply are the pests…

In this article, we’re going to identify which terrarium insects and bugs are friendly (and which are not) and where to find some really cool varieties.

Ready to unearth some gems? Let’s go.

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First up, we’re starting with the good guys.

Bioactive terrarium bugs are a fantastic addition to any terrarium setup.

After all, being able to decompose organic matter – and process it to become available nutrients for your live plants – is part of being a truly self-sustaining terrarium.

What makes this possible is the microorganisms (bacteria and fungi) and the microfauna (insects and bugs) that are able to help the decomposition process along. The term for such a thing is a bioactive terrarium.

Here are the best bugs for terrariums. 👇

1. Springtails in Terrariums

Springtails are the single most effective bioactive terrarium bug.

Conveniently, they’re also the easiest to get started with.

Requiring almost no care at all, springtails in terrariums are the perfect compromise for someone who wants the mold-fighting, terrarium-cleaning dream team (without the additional needs of a pet).

These tiny critters are only 1/16″ at full size, and they’re really more jumpers than they are crawlers (hence the name).

It’s always best to use them in an enclosed terrarium, but more to meet their moisture requirements than stop them escaping. We’ve never had issues with that.

Springtails are detritivores, which means they love to feed on dead organic plant matter, but their favorite food is fungi. So, in the absence of any mushrooms in your terrarium, they’re going to feed on the most abundant source – mold.

That’s right, you can say goodbye to those awful mold blooms with a colony of springtails!

Different varieties can be found to best match your terrarium conditions (or color preferences). But temperate springtails do fantastically well in tropical terrarium conditions, too – so it’s not make or break.

We sell the most tried-and-tested species in the industry – Folsomia candida, otherwise known as Temperate White Springtails.

The amount of springtails you’ll need depends on the size of your terrarium, but even just a small colony can be hugely beneficial. Honestly, they tend to reproduce very quickly, so you don’t need to always start with a giant culture.

A few springtails and a little bit of patience go a long way!

2. Isopods in Terrariums

Just like springtails, isopods will readily feed on decaying organic matter and help keep your terrarium clean and fertile (in fact, springtails and isopods make a great team).

Easily the best thing about isopods is their huge diversity in shape, size, and colors.

However, their environmental needs can differ quite a lot, too, so it’s important to get the right species for your setup.

Tropical species are a good starting point, as you’ll want an isopod culture that thrives in a closed terrarium’s warm temperatures and high humidity.

• Dwarf White Isopods make an amazing cleanup crew for small and large terrariums alike. They’re adaptable, efficient, and the next smallest critters after springtails.
• Or, the larger varieties (e.g., Powder Orange Isopods and Dairy Cow Isopods) make great clean-up crews for larger terrariums and vivariums.

There is a wide variety of terrarium-suitable species, those are just a select few bioactive choices.

If you prefer to have a cool isopod pet in your terrarium (and don’t expect/need it to do much cleanup work) then you’ve even more funky isopod species to choose from.

Next up, we have the bioactive bugs with very niche use cases.

3. Worms in Terrariums

Worms are fantastic at aerating the soil and reaching areas that other bioactive bugs won’t.

So, should you put worms in a terrarium? In most cases, probably not.

• Despite always being beneath the soil, they can make a real mess on the glass.
• Different worm species require different levels of depth and space, which are difficult to achieve in a terrarium.
• They’re a little too effective at consuming organic material. They’ll often chew through your substrate itself, turning into a thick mush.

For larger projects, there’s value in adding some terrarium worms. But I wouldn’t bother for your average terrarium; I don’t think the benefits outweigh the negatives.

4. How About Millipedes?

Much like pill bugs, millipedes are effective decay-munching machines… that unfortunately, also run the risk of feeding on your plants.

Being larger (and a touch more challenging to keep) than isopods, they don’t see nearly as much use in terrariums and vivariums.

That said, millipedes do make for cool pets, and they are solid bioactive cleaners.

I’ve seen them used in larger setups, and you can supplement their diets with apple slices and such. So, hopefully, if there’s no lack of food, then they wouldn’t turn to your plants!

Check out my terrarium millipede guide for the full rundown.

Snails, Slugs, and Beetles

The likes of snails, slugs, and beetles will all love being in a terrarium.

Small, easy to keep, and full of diversity, why not go for it?

Well, just bear in mind that all of the above are inclined to eat plants from time to time. Much like the millipedes, if you’re feeding them with supplementary food, then they may leave your plants alone. 

Plant choice is critical here, too, as there are plants out there that snails tend to avoid. Check out my Snail Terrarium Guide for my top plant picks.

In fact, roaches might be a better choice if you want to be extra careful.

Mantis and Ladybugs

One way to avoid collateral plant damage is to pick carnivorous bugs!

Naturally, this completely changes the game in terms of how you care for them. 

Praying mantes are a common (and super cool) choice that can work well in an insect terrarium.

Ladybugs, however, are voracious aphid-eating machines and will quickly run out of available food. I wouldn’t be surprised if a ladybug devoured a springtail population given the chance.

Just note that any carnivorous insects might well eat your beneficial terrarium bugs. So popping them in with your usual cleanup crew is probably a bad idea…

Spiders and Scorpions

Okay, so I know spiders and scorpions aren’t insects or bugs, but they definitely fall into the same line of questioning as the rest of the critters on this list. 

These burrowing pets can both thrive in a targeted terrarium environment. But that’s definitely way out of my expertise (and comfort zone).

Check out my terrarium pets guide and insect and bug pets guides for more help.

Finally, we move from pets to terrarium pests.

Spotted any tiny unidentified flying bugs in your terrarium?

They’re probably one of the bad bugs, I’m afraid. Gnats, mites, and mealybugs are all known plant parasites that can hitch a ride into terrariums via plants and substrate.

These have different negative effects on plants, ranging from generally harmless (just unsightly and annoying) to vitality-sapping swarms.

Plus, though completely airtight terrariums are immune to external invaders, ventilated setups are not.

I’d be particularly wary of overfeeding any of your other beneficial bugs (especially with wet foods like fruit) as these can attract pests. Little and often is best!

Unfortunately, getting rid of bugs in terrariums can be a challenging task and often involves significant interventions, from quarantining plants to swapping out substrates. 

Sometimes, even just starting over.

The answer is no, they’re not a strict necessity, and I’ve happily grown many a terrarium with bugs and without them.

That said, these beneficial terrarium insects really can make the whole care process much easier.

I’d absolutely recommend at least a handful of springtails in every setup, and isopods bring a lot to the table too.