Kritter Keepers

If you have walked into any pet store in the last thirty years, you have seen Kritter Keepers. These rectangular plastic enclosures with ventilated lids are probably the most common first enclosure for anyone getting into invertebrate keeping, and there is a good reason for that. They are cheap, widely available, come in multiple sizes, and provide a clear view of whatever animal lives inside. For a lot of keepers, a Kritter Keeper is the first real enclosure they buy, and for certain species and situations they work perfectly well.

The appeal goes beyond price. Kritter Keepers are lightweight, stack reasonably well, and the lids snap on securely enough to contain most terrestrial invertebrates. You can find them at nearly every pet store, department store pet section, and online retailer, which means replacement parts and additional units are always accessible. For keepers who need a quick, functional enclosure without building something custom or ordering specialty acrylic, these boxes fill that role immediately.

But there is a significant catch that catches new keepers off guard, and it is the reason experienced keepers often move away from Kritter Keepers for humidity-dependent species. The ventilated lid design that makes them useful for reptiles and amphibians also makes them terrible at retaining moisture. That big grid of ventilation slots in the lid lets humidity escape rapidly, and for species that need sustained high humidity like tropical tarantulas, many mantis species, and most millipedes, a standard Kritter Keeper dries out faster than you can keep up with.

Keepers regularly debate whether Kritter Keepers are good enclosures or bad ones, and the real answer is that they are the right tool for some jobs and the wrong tool for others. An arid-adapted scorpion or a desert beetle does perfectly well in one. A humidity-sensitive Avicularia or a tropical centipede does not. Understanding what these enclosures do well and where they fall short lets you use them where they make sense and avoid them where they do not.

This article covers the practical reality of keeping invertebrates in Kritter Keepers, including which species they suit, how to modify them for better humidity retention, their limitations compared to other enclosure options, and when you should choose something else entirely.

Kritter Keepers are injection-molded plastic enclosures manufactured by several companies, with the Lee's brand being the most recognizable in North America. They come in sizes ranging from roughly the dimensions of a large sandwich container up to enclosures suitable for medium-bodied adult tarantulas or small scorpion species. The plastic is clear, moderately durable, and lightweight. The lids feature a large ventilated panel and a hinged feeding door that opens without removing the entire lid, which is useful for dropping in prey items without risking an escape.

The ventilation system is both the defining feature and the primary limitation of these enclosures. The lid contains a grid of wide slots that allows generous airflow, which prevents stagnant air and mold growth effectively. For species that tolerate or prefer lower humidity, this ventilation is ideal. However, for any species requiring sustained humidity above sixty percent, the ventilation rate is simply too high. Moisture escapes through the lid faster than misting can replace it, and the substrate dries from the top down within hours in a dry room. This is not a flaw in the product. It was designed for temporary housing and species that do not need tropical conditions.

Modifying Kritter Keepers for improved humidity retention is straightforward and something most keepers learn to do early in their hobby. The simplest approach is covering a portion of the ventilated lid with plastic wrap, packing tape, or a cut piece of acrylic sheet. Blocking fifty to seventy-five percent of the vent slots dramatically reduces moisture loss while still allowing enough air exchange to prevent stagnation. Some keepers replace the entire lid with a custom-cut acrylic panel with smaller, drilled ventilation holes. Others use damp sphagnum moss pressed against the inside of the lid to act as a humidity buffer.

The latch system on Kritter Keeper lids varies by manufacturer and model, and not all of them are escape-proof for determined invertebrates. Small tarantulas can squeeze through gaps between the lid and the container body if the fit is loose, and strong species like centipedes can push through latches that do not lock firmly. Checking the lid fit before adding any animal is essential, and adding a strip of tape across the lid seam provides extra security for species known to test enclosure boundaries.

The feeding door on the lid is a genuine convenience feature that other enclosure types often lack. Being able to drop in a cricket or remove a water dish without taking the entire lid off reduces the chance of startling the animal and limits escape opportunities. For keepers maintaining multiple enclosures, this small time savings during feeding rounds adds up significantly.

From a cost perspective, Kritter Keepers remain among the least expensive enclosure options available. A medium-sized unit costs a few dollars at retail, making them accessible for keepers on a budget or those housing large collections where enclosure costs multiply quickly. The trade-off is that you get a general-purpose container rather than a purpose-built invertebrate enclosure, and for many species the modifications needed to make it suitable cost additional time and materials.

Desert and arid-adapted arachnids are the best match for unmodified Kritter Keepers. Species like Aphonopelma chalcodes, Hadrurus arizonensis, and many other dry-climate tarantulas and scorpions thrive in the high-ventilation environment these enclosures provide. The generous airflow prevents the stagnant, humid conditions that stress desert species, and the wide opening makes substrate changes and maintenance easy. For these animals, a Kritter Keeper is genuinely a good enclosure choice without any modifications needed.

Tropical and humidity-dependent arachnids require modifications or an entirely different enclosure. Species like Caribena versicolor, Monocentropus balfouri, and tropical scorpions like Heterometrus species need sustained humidity that an unmodified Kritter Keeper simply cannot maintain. If you choose to use one for these species, covering most of the ventilation, adding deeper damp substrate, and misting frequently can make it workable, but many keepers find it easier to use an enclosure designed for humidity retention rather than constantly fighting the ventilation on a Kritter Keeper.

Mantis species have a mixed relationship with Kritter Keepers depending on whether the species is temperate or tropical. Temperate mantis species like Tenodera sinensis do well in them, while tropical flower mantises and orchid mantises need the humidity modifications described above. The vertical space in a Kritter Keeper is limited compared to purpose-built mantis enclosures, which can be a problem for large species that need height for molting. Orienting a Kritter Keeper on its side to create a taller space is a workaround some keepers use, though it requires securing the lid differently.

Millipedes, centipedes, and other myriapods generally need more humidity than Kritter Keepers provide without modification. Giant millipedes in particular need consistent moisture in their substrate and ambient air, and the rapid drying that occurs through the ventilated lid works against them. Modified Kritter Keepers can house myriapods adequately, but keepers maintaining large millipede or centipede collections often prefer storage containers with drilled ventilation because those retain moisture more predictably.

Isopods, beetles, and roaches represent groups where Kritter Keepers can work well depending on the specific species. Hardy isopod species like Porcellio scaber tolerate the ventilation, while tropical Cubaris do not. Darkling beetles and many cockroach species do fine in them. The key question for any species is whether the ventilation rate matches the humidity requirement, and if it does not, whether you are willing to modify the lid or would rather start with a more suitable container.

Before buying Kritter Keepers for your collection, identify which species you plan to house in them and confirm that the ventilation characteristics match those species' needs. Buying a dozen Kritter Keepers because they are on sale only to discover that your species require humid conditions wastes money and creates modification work you could have avoided. If you keep a mix of arid and tropical species, Kritter Keepers may work for half your collection while the other half needs different enclosures.

Setting up a Kritter Keeper follows the same basic steps as any enclosure. Add substrate appropriate to your species at the correct depth, place hides and furnishings, establish your moisture zones, and check the lid fit for security. The one additional step specific to Kritter Keepers is deciding whether to modify the ventilation before adding the animal. Make your lid modifications before the enclosure is in use, not after you notice your animal is dehydrating. Covering vent slots with tape or plastic wrap takes a minute and should be part of setup rather than troubleshooting.

Maintenance in Kritter Keepers follows standard protocols with one caveat. The high ventilation rate means you will likely need to mist or add water more frequently than you would with a less ventilated enclosure. Build this into your routine rather than discovering it reactively. Check substrate moisture every two days for species that need humidity, and every four to five days for arid species. The feeding door makes prey delivery and water dish access convenient, so take advantage of it rather than removing the entire lid for routine tasks.

When a Kritter Keeper is not working for a particular animal, the signs are consistent. The substrate dries out within a day despite regular misting. The animal clusters in the dampest corner constantly rather than using the full enclosure. Molts fail because humidity drops below the threshold the animal needs. These are not problems you can solve by misting more aggressively. They indicate that the enclosure ventilation does not match the species, and either heavy modification or a different enclosure is the answer.

For collections with many Kritter Keepers, stacking and organizing them efficiently matters for daily maintenance. They stack reasonably well by size but the lids can shift under weight, so placing a thin board or piece of cardboard between stacked layers prevents lid displacement. Label each enclosure on the side rather than the lid so the label stays with the container during lid removal.

Using unmodified Kritter Keepers for humidity-dependent species and then blaming the species when things go wrong is the most common mistake associated with these enclosures. Keepers buy a Kritter Keeper because it was recommended online without considering whether the recommendation accounted for their specific species, and then struggle to maintain humidity despite misting three times a day. The enclosure is working exactly as designed. It ventilates aggressively. That is what it does. If your species needs humidity, modify the lid or use a different enclosure.

Not checking lid security before adding an animal leads to escapes that are difficult to recover from, especially with fast-moving species like centipedes or old world tarantulas. Kritter Keeper lids vary in fit quality between manufacturers and even between units from the same manufacturer. A lid that feels secure to your fingers may have a gap large enough for a determined invertebrate to exploit. Test the fit, check for gaps along the seam, and add tape if anything feels loose. Losing an animal to a preventable escape is frustrating and completely avoidable.

Relying on the feeding door for all access is a mistake some keepers make because they never want to fully open the enclosure. The feeding door is designed for dropping in food and small maintenance tasks, but it is too small for substrate changes, deep cleaning, or removing established webbing. Avoiding full lid removal because of escape concerns leads to enclosures that accumulate waste, develop mold in corners, and deteriorate in substrate quality over time. Use the feeding door for what it is good for and do full maintenance with the lid removed when necessary.

Overstacking Kritter Keepers without supports between layers causes lids to compress and pop open under the weight above them. This is how mass escapes happen in collections stored on shelving units. Each stack should have a rigid surface between layers, and stacks should not exceed three or four units high depending on the size. A collapsed stack in the middle of the night means multiple open enclosures and animals loose in your animal room.

Buying the wrong size Kritter Keeper because the next size up costs a few dollars more is false economy that hurts the animal. A large tarantula crammed into a small Kritter Keeper cannot move, dig, or web normally. A tiny sling lost in an oversized one cannot find food. Size the enclosure to the animal, not to your budget preferences. The difference between appropriate and inappropriate sizes is usually only a dollar or two at retail.

Kritter Keepers are a tool, and like any tool they work well for certain jobs and poorly for others. Their strengths are availability, affordability, clear visibility, convenient feeding doors, and adequate ventilation for arid-adapted species. Their weakness is a single characteristic that defines the entire product: they ventilate too aggressively for humidity-dependent species. Every decision about using a Kritter Keeper flows from that one fact.

If your species tolerates or prefers lower humidity, a Kritter Keeper is a solid, functional enclosure that does not need any apology. Desert tarantulas, arid scorpions, temperate mantis species, and hardy isopods all do well in them. There is nothing wrong with using affordable, accessible enclosures when they match your animals' needs, and anyone telling you that cheap enclosures are inherently bad is confusing price with suitability.

If your species needs humidity, either modify the Kritter Keeper to retain moisture or choose a different enclosure from the start. Modifications are simple and effective. Covering vent slots takes a minute and transforms the humidity dynamics of the enclosure. But if you are modifying every Kritter Keeper extensively, consider whether purpose-built enclosures or modified storage containers would serve your collection better with less ongoing effort. There comes a point where the modification work exceeds the cost savings, and at that point a different enclosure choice makes more practical sense.

The practical takeaway is to match enclosures to species rather than defaulting to one enclosure type for everything. A keeper with a diverse collection will likely use Kritter Keepers for some animals, deli cups for juveniles, acrylic enclosures for display species, and modified storage containers for humidity-dependent animals. Using the right enclosure for each situation is smarter than committing to one product line and forcing every animal into it. Kritter Keepers have earned their place in the hobby because they solve a real problem, affordable and accessible housing, and they do it well enough for a significant range of species. Know what they are good at, know their limits, and use them accordingly.