Plastic Enclosures

Plastic enclosures are the backbone of invertebrate keeping, housing everything from tarantula slings in two-ounce deli cups to giant millipedes in modified storage tubs. No other enclosure material offers the same combination of availability, affordability, ease of modification, and practical functionality that makes plastic the default choice for the majority of keepers worldwide. Whether you are raising your first tarantula or managing a collection of several hundred animals, plastic enclosures in various forms will likely make up most or all of your housing.

The range of plastic containers used in the hobby is enormous. Deli cups, critter keepers, modified food storage containers, shoe boxes, sweater boxes, large storage tubs, and purpose-built acrylic enclosures all fall under this umbrella. Each serves different species and life stages, and understanding which type works for which application saves money, prevents escapes, and keeps animals healthy. The versatility of plastic is its greatest strength because you can find or modify a container for virtually any invertebrate at any size.

Plastic enclosures matter for animal welfare because the container is the animal's entire world. A well-chosen plastic enclosure that holds humidity appropriately, ventilates adequately, and provides the right amount of space allows an invertebrate to behave naturally and thrive. A poorly chosen one that dries out too fast, holds stagnant air, or offers the wrong dimensions creates chronic stress that manifests as refusal to eat, failed molts, and shortened lifespans. The container itself is cheap. The consequences of choosing the wrong one are not.

New keepers frequently ask whether they should invest in glass terrariums or expensive acrylic setups, and for most species the honest answer is that a properly modified plastic container outperforms an expensive enclosure that was not designed with invertebrate needs in mind. The key is understanding how to select the right type of plastic enclosure for your specific animal and how to modify it to meet the ventilation and humidity requirements that species demands.

This article covers the full range of plastic enclosure options available to invertebrate keepers, how to choose the right type for different species and life stages, modification techniques for ventilation and access, and maintenance practices that keep plastic enclosures clean and functional over years of use.

The fundamental principle behind plastic enclosure selection is matching the container's dimensions, ventilation characteristics, and moisture retention to the species you intend to house. Terrestrial tarantulas need floor space more than height, with a width roughly three times the animal's leg span providing adequate room for a burrow, water dish, and movement. Arboreal species need vertical space with anchor points for webbing, which means taller containers oriented on their sides or purpose-built tall enclosures. Fossorial species need containers deep enough to accommodate several inches of substrate for burrowing. Getting the basic orientation and dimensions right is the first decision, and everything else follows from there.

The types of plastic used in common enclosures matter more than most keepers realize. Polypropylene and polyethylene containers, which include most food storage containers and deli cups, are chemically inert, easy to clean, and safe for all invertebrate species. Polystyrene, found in some disposable containers, is more brittle and can crack under stress. Acrylic enclosures offer excellent clarity for display purposes but scratch easily and cost significantly more than utilitarian options. For most keepers running functional collections rather than display setups, food-grade polypropylene containers provide the best combination of durability, cost, and safety.

Modifying plastic enclosures for ventilation is the most important skill in invertebrate housing. The standard approach involves drilling or melting holes in the container using a soldering iron, drill, or heated nail. The size, number, and placement of ventilation holes determine how quickly the enclosure exchanges air and how well it retains humidity. Species from humid tropical environments need fewer, smaller holes to maintain moisture, while species requiring drier conditions or high airflow need more extensive ventilation. Cross-ventilation, where holes are placed on opposite sides of the enclosure, promotes better air circulation than holes concentrated in one area.

Secure lids and closures prevent escapes, which is a constant concern with invertebrate enclosures because many species are surprisingly strong, persistent, or small enough to exploit gaps that seem insignificant to the keeper. Snap-lock containers with tight-fitting lids work well for most applications. Screw-top deli cups are excellent for slings and small species. Any container with a push-on lid should be tested by pressing firmly around all edges to identify areas where the fit is loose enough for a determined animal to push through. Adding small clamps or weights to lids that do not lock provides additional security for strong species.

Cleaning plastic enclosures between uses is straightforward. Wash with hot water and a mild detergent, rinse thoroughly, and allow to dry completely before setting up for a new animal. Avoid harsh chemicals, bleach, or disinfectants that can leave residues toxic to invertebrates even after rinsing. For enclosures that housed sick animals, a dilute white vinegar soak followed by extensive rinsing provides reasonable sanitization without chemical risk. Plastic containers that have become deeply scratched, stained, or warped should be retired and replaced rather than reused, since scratches can harbor bacteria and warped lids compromise escape security.

As collections grow, standardizing your plastic enclosure types simplifies maintenance enormously. Choosing two or three container types that cover your range of species and sticking with them means lids are interchangeable, modifications become routine, and shelf space can be planned efficiently. Experienced keepers with large collections often buy containers in bulk, pre-modify a batch at once, and keep a stock of ready-to-use enclosures available so that rehousing or setting up for a new animal takes minutes rather than hours.

Tarantulas represent the largest user base for plastic enclosures in the hobby, and the progression from sling to adult demonstrates how plastic containers scale across life stages. Slings start in two-ounce or four-ounce deli cups with pinhole ventilation and a tiny water dish or moistened substrate corner. Juveniles graduate to sixteen-ounce or thirty-two-ounce deli cups or small snap-lock containers. Subadults and adults move into appropriately sized storage containers, critter keepers, or purpose-built acrylic enclosures depending on the species' adult size. Scorpions follow a similar progression with the added consideration that fossorial species need containers deep enough for substantial substrate layers.

Mantises and stick insects require tall enclosures with mesh or screen ventilation for adequate airflow, which makes them trickier to house in standard plastic containers without significant modification. Many mantis keepers use tall deli cups or cylindrical containers with mesh lids for nymphs, graduating to net cages or heavily ventilated plastic enclosures for adults. Stick insects do well in tall plastic containers or modified storage bins oriented vertically, with mesh panels replacing large sections of the lid or sides to provide the airflow these species demand.

Millipedes and centipedes do well in wider, lower-profile plastic containers with moderate ventilation and secure lids. Millipedes need substantial substrate depth for burrowing and feeding on decaying organic matter, so the container must be deep enough to accommodate four to six inches of substrate while still leaving airspace above. Centipedes require extremely secure enclosures because they are fast, strong, and capable of exploiting any gap in a lid or ventilation opening. Many experienced centipede keepers use containers with locking lids and cover ventilation holes with fine metal mesh rather than relying on the plastic alone.

Hermit crabs, terrestrial isopods, and other land-dwelling crustaceans benefit from larger plastic enclosures that hold humidity well while still allowing some air exchange. Modified storage tubs with small ventilation holes work well because the larger air volume inside the container creates a more stable microclimate than small enclosures can maintain. Isopod keepers often use shoe box or sweater box sized containers with minimal ventilation to maintain the high humidity these animals need, while hermit crabs require larger setups with enough space for climbing structures, substrate for digging, and pools for soaking.

Across all species groups, the plastic enclosure serves the same basic function. It contains the animal securely, maintains appropriate environmental conditions, and allows the keeper to observe and access the animal for feeding and maintenance. The specific container type, size, and modification approach changes with the species, but the underlying principles of security, ventilation balance, and appropriate dimensions remain constant.

Before purchasing enclosures, make a list of every animal you need to house including its current size, expected adult size, and whether it requires terrestrial, arboreal, or fossorial setup. This prevents buying containers you will outgrow in three months and helps you identify opportunities to standardize across species with similar needs. Source containers in bulk when possible because buying twenty deli cups from a restaurant supply store costs a fraction of what you would pay buying them individually from pet shops.

Modifying enclosures in batches is far more efficient than modifying one at a time. Set up your workspace with your soldering iron or drill, mark your ventilation pattern on the first container, and replicate it across the entire batch. A consistent modification pattern ensures predictable humidity and airflow performance across all enclosures of the same type, which makes environmental management much more predictable as your collection grows. Let freshly melted or drilled enclosures air out for a day or two before adding substrate and animals to ensure any residual plastic fumes have dissipated.

Daily maintenance for plastic enclosures involves quick visual checks of water dishes, ventilation holes, and lid security. Weekly tasks include spot cleaning waste, checking substrate moisture levels, and removing uneaten food. Monthly tasks should include a more thorough inspection of the enclosure for cracks, warped lids, clogged ventilation holes, and any signs of mold or bacterial growth in the substrate. Plastic containers are easy to replace, so do not hesitate to retire one that shows signs of structural compromise.

Troubleshooting common problems with plastic enclosures usually involves humidity management. If the enclosure dries out too quickly, you need fewer or smaller ventilation holes, or you need to add ventilation only on one side rather than both. If condensation is heavy and the air inside smells stale, you need more ventilation or larger holes. Many keepers find the right balance through trial and error with their specific room conditions, adjusting ventilation with small pieces of tape over existing holes to reduce airflow or adding new holes to increase it.

Managing a large collection of plastic enclosures requires organization and labeling. Mark each container with the species name, acquisition date, last feeding date, and last maintenance date using a label maker or tape and permanent marker. Arrange enclosures on shelving by species group or maintenance schedule so you can work through feeding and watering systematically rather than hunting through a disorganized shelf of identical-looking containers.

Choosing enclosures based on what looks good on a shelf rather than what the animal actually needs is a persistent problem, especially among newer keepers influenced by elaborate display setups they see online. A beautifully arranged acrylic terrarium with decorative substrate and artificial plants means nothing if the ventilation is wrong for the species or the dimensions force the animal into an unnatural posture. Function comes first. If the enclosure meets the animal's needs and also looks attractive, that is a bonus, but the animal's requirements always take priority over aesthetics.

Insufficient ventilation kills more invertebrates in plastic enclosures than almost any other housing error. A sealed or nearly sealed container traps moisture and carbon dioxide, creating conditions that promote mold growth, bacterial proliferation, and respiratory stress. Keepers who are afraid of their enclosure drying out sometimes err so far in the direction of moisture retention that they create a stagnant, unhealthy environment. Every plastic enclosure needs some ventilation, even those housing humidity-dependent species. The question is how much, not whether.

Using containers with lids that do not close securely results in escapes that range from inconvenient to dangerous depending on the species. A missing tarantula sling is frustrating but ultimately harmless. A missing centipede is a legitimate safety concern. Test every lid before placing an animal inside by pressing around the entire perimeter and attempting to slide the lid sideways. If you can shift the lid with moderate finger pressure, the animal can shift it too. Add clips, weights, or replace the container entirely.

Failing to account for growth means frequent rehousing that stresses both the animal and the keeper. A tarantula sling that needs rehousing every two months because the keeper keeps choosing containers only slightly larger than the current one wastes time, money, and the animal's energy. Size the enclosure for the animal's expected size over the next six to twelve months rather than its current size, and you will rehouse less frequently while still providing appropriate space at each stage.

Neglecting to clean and inspect enclosures regularly allows problems to accumulate until they become serious. Mold colonies establish in damp substrate corners, waste products build up around burrow entrances, and small cracks in container walls widen until they become escape routes. A quick weekly inspection catches these issues when they are still trivial to address. Waiting until the enclosure smells bad or the animal shows signs of distress means the problem has been affecting the animal's health for longer than it should have.

Plastic enclosures work for invertebrate keeping because they are affordable, widely available, easy to modify, and functionally superior to more expensive alternatives for the vast majority of species and situations. The keeper who masters plastic container selection and modification can house any invertebrate in the hobby effectively, from the smallest sling to the largest adult, without spending a fortune on specialized terrariums. This practical, no-nonsense approach to housing is what makes large collections manageable and invertebrate keeping accessible to people at every budget level.

The most important skills in working with plastic enclosures are choosing the right size and type for each species and modifying ventilation to balance airflow with humidity retention. These two factors determine whether the enclosure creates an appropriate environment or a problematic one, and they are entirely within the keeper's control. Take the time to learn how your specific animals respond to different ventilation configurations in your room conditions, and you will develop an intuitive sense for what works that serves you across every species you keep.

Species-specific housing research matters even when the enclosure material is the same across your entire collection. A plastic container is just a container until you modify it, fill it with appropriate substrate, and configure it to meet the needs of the animal going inside. The modification approach for an arboreal tarantula enclosure differs substantially from a fossorial scorpion setup, even if both start as the same brand of snap-lock container. Know your species, modify accordingly, and the humble plastic container becomes exactly the habitat your animal needs.

Investing time in learning to work with plastic enclosures efficiently pays off every time you acquire a new animal, rehouse a growing juvenile, or set up an enclosure for a species you have not kept before. The skills transfer directly, the materials are always available, and the results are reliable. It is not glamorous, but it works, and in invertebrate keeping, what works is what matters.