Heating Isopods: Equipment and Setup

Plenty of UK isopods need no heating at all - natives and most Mediterranean Armadillidium live well in a heated room year-round. But Cubaris need warmth through the colder months, Dwarf Whites for part of the year, and warmer-leaning species such as Dairy Cows, Powders and Clowns breed better with some additional heat from autumn to spring, which is where the right equipment matters. Ardentiella are the genus most often heated by mistake and are covered below. This guide focuses on the practical equipment side: what to buy, how to install it, and how to troubleshoot common heating issues.

For species-specific temperature ranges and seasonal guidance, see our isopod temperature range guide. This article focuses specifically on the equipment side.

Do Your Isopods Actually Need Heating?

The first question. Not all isopod species need supplementary heating in UK homes. A quick guide:

UK-native species (Porcellio scaber, Oniscus asellus, native Armadillidium vulgare) - NO heating needed. UK ambient is their natural climate
Mediterranean temperate species (most Armadillidium hobby morphs, P. expansus and similar Porcellio) - rarely need heating in heated UK homes. May benefit from gentle warmth in unusually cold winter periods
Warmer-leaning species (Dairy Cows, Powders, Clowns, P. hoffmannseggii, P. magnificus) - tolerate a heated room but breed better at their ideal, which starts at 20°C or more, so additional heat from autumn to spring helps
Cubaris - need heating through the colder months at least in UK homes
Dwarf Whites (Trichorhina tomentosa, 22-28°C) - gentle heat for part of the year in most homes
Ardentiella - NO heat mat or cable. Tropical in origin, but they tolerate 19-26°C, do best at about 20-23°C and struggle above 26°C, so keep them in a heated room, which sits at the cool edge of their range in winter; added heat is a common way to lose them. This reverses advice we gave until recently - see our Ardentiella care guide

The number this whole question turns on: what a UK home actually measures

Most heating advice you will read online was written by somebody living somewhere else, and the ambient temperature they took for granted is not ours. So here is the measured figure. The Energy Follow-Up Survey put temperature loggers in 823 English homes for a year, recording every twenty minutes:

Whole dwelling, heating season (October to April): 19.0°C
Living room 19.3°C, bedroom 18.9°C
December, the coldest month: 18.1°C
July and August, the warmest: 21.5°C
26% of homes sit below 18°C through the heating season; only 7% exceed 22°C

Now set that against what isopods actually choose. Given a thermal gradient to walk around in, they pick the low twenties: 22-23°C for Armadillidium vulgare (Refinetti 1984), 20.9°C for Porcellio scaber (Antoł and colleagues 2019), an optimum of 21-25°C across three Porcellio laevis populations (Castañeda 2004). Three species, three continents, forty years apart, same answer.

So a British home sits two to six degrees below where these animals would put themselves. That is the honest case for heating, and it is a stronger one than "they are tropical". It is a case for faster breeding, not for keeping them alive: natives and most Mediterranean Armadillidium live and breed in a heated room without it. It also tells you where to stop.

Where the evidence for warmth runs out

Brood development in P. scaber takes 59 days at 15°C and 23 days at 22°C - a genuine 2.6-fold acceleration (Horváthová and colleagues 2015). But 22°C was the warmest arm of that experiment. Other species have been timed warmer: Porcellio laevis broods took about 24 days at 25°C against 51 at 15°C (Ghemari and colleagues 2017), and we know of no study that has timed a brood at a steady temperature above about 27°C. What has been measured above that is cost: raising P. scaber from 20°C to 28°C more than doubled mortality, from 9.4% to 23.4% (Römbke 2011), and at 27-31°C the same species took more than twice as long to cross a maze (Ďurajková 2022). Mediterranean Porcellionides shrugged both off.

Where you heat, heat to reach the low twenties. There is no evidence that pushing past them helps, and measured harm by 28°C. And note the ceiling people quote - a critical thermal maximum around 40°C - is a ramping assay measured over minutes. It is not a temperature anything survives for a week.

Unheated rooms - spare rooms, garages, conservatories - drop well below the figures above, particularly in winter, and are where a thermostatically controlled mat or cable earns its keep.

Species-Specific Temperature Ranges

The first thing to know: there's no universal "isopod temperature." Different species evolved in different climates and have different preferences. The general "68-82°F" range you might see in older care articles is too broad to be useful.

UK-Native and Cool-Temperate Species

Native woodlice (Porcellio scaber, Oniscus asellus, native Armadillidium vulgare) - evolved for UK conditions:

Preferred range: P. scaber 17-26°C, Oniscus asellus 15-25°C, A. vulgare 18-24°C
Tolerates: Down to ~10°C without major issues; mortality in P. scaber climbs by 28°C
Heating needed: Rarely. UK ambient room temperature is fine year-round

Mediterranean Temperate Species

Most common Armadillidium hobby morphs (Jelly Bean, Magic Potion, A. depressum, A. gestroi, A. granulatum) and the cooler Spanish Porcellio (P. expansus, P. ornatus) - evolved for warmer European climates than the UK:

Preferred range: 18-24°C for most of the Armadillidium (A. depressum 17-26°C, A. granulatum cooler at 18-22°C), 18-26°C for P. expansus and P. ornatus
Tolerates: Down to ~15°C with reduced activity; up to ~27°C briefly
Heating needed: Usually fine at UK room temperatures, but occasional supplementary heating in winter helps maintain breeding activity in colder homes

Warmer-Leaning Species

Species whose ideal starts above an average British winter room: Dairy Cows and the other Porcellio laevis morphs, Powders (Porcellionides pruinosus), the Spanish giants P. hoffmannseggii and P. magnificus, and Clowns (Armadillidium klugii):

Preferred range: 20-26°C (P. magnificus to 28°C; Clowns 22-26°C)
Tolerates: A normally heated room, where they live well but breed more slowly
Heating needed: Not to keep them alive, but additional heat from autumn to spring keeps them breeding well. The Clowns' range starts above an average home even in summer, so gentle warmth speeds up a slow colony

Cubaris - and why "tropical" is the wrong word

The Cubaris kept in the hobby (Rubber Ducky, Panda King, Crazy Horse, and similar Cubaris morphs):

Preferred range: about 22-26°C, by species (the Panda King's care panel reads 21-27°C), so check each listing
Tolerates: down to ~20°C with reduced activity
Heating needed: yes, through the colder months at least. An English home measures 19.0°C in the heating season and only 21.5°C at the height of summer, so ambient sits below this range through the colder months and at best near the bottom of it in summer

But "tropical" misleads people into overshooting. Sellers place these animals in limestone karst country, and shaded karst in Southeast Asia is not hot. When the fauna of the Dark Cave at Batu Caves in Malaysia was surveyed in 1967 - a survey that recorded terrestrial isopods living in it - the cave interior held a mean of 24.5°C with a range across the whole year of 23.0 to 25.0°C. The forest outside reaches 29-30°C most afternoons. Broader work on tropical caves finds interiors tracking the local mean annual surface temperature with roughly half the amplitude.

So an animal living in shaded karst is buffered against the tropical daytime peak. The defining feature of that habitat is stability, not heat - which is why the measured preference of every isopod anyone has tested (21-25°C) and the temperature inside that cave (23-25°C) agree with each other, and the hobby's 26-28°C agrees with neither.

One caveat we would rather state than hide: there is no published physiology for Cubaris at all - no thermal preference study, no lethal limits, nothing. The figures above are inferred from the cave and from temperate relatives. Anyone quoting you a precise Rubber Ducky optimum is doing the same inference with more confidence than it deserves.

Ardentiella (formerly Merulanella) - the genus this guide used to get wrong

Vietnamese species (Scarlet, Yellow Phoenix, Lava, Batman, Pastel, Ember Bee and similar Ardentiella morphs):

Preferred range: about 20-23°C
Tolerates: 19-26°C, so a normally heated UK room, which sits at the cool edge of that range in winter; struggles above 26°C
Heating needed: No heat mat or cable; a heated room is all they need. We recommended a mat for this genus until recently and were wrong. In this country heat is the hazard and cold is not, and added heat is a common way to lose the colony - see our Ardentiella care guide, linked above

The Recommended Equipment: Heat Mats and Heat Cable

Heat mats are the standard heating solution for isopod enclosures. They provide gentle, consistent warmth without desiccating the enclosure or creating problematic light exposure.

Heat cable does the same job, and there are two situations where it is the better answer. On a small tub, even a small mat can cover more of one side than you want, which flattens the gradient the colony needs; a cable warms only the narrow strip it runs along, so the warm zone is easier to keep small. And across a rack of several tubs, one cable on one thermostat costs less than a mat for every box (see Multi-Enclosure Setups below). A mat is the simpler choice for a single large enclosure. Cable is sold at a higher wattage than a mat because the heat is spread along its length, so match the length to the run rather than the wattage to the tub. Whichever you use, the rules do not change: on the side or behind, never underneath, and always on a thermostat.

What to Look For in a Mat

Low wattage - 7W or 10W is sufficient for typical isopod tubs (3-15 litres). Higher wattage creates dangerous hot spots
Adhesive backing - easy to mount on the side of plastic or glass enclosures
Reasonable surface area - should cover roughly one-third to one-half of the enclosure side. Smaller is fine if you only need a warm spot rather than uniform warmth
Reputable brand - Habistat, Pro Rep, and Komodo are common UK brands. Cheap unbranded mats can fail catastrophically (overheat or burn out)

Critical: Always Use a Thermostat

Heat mats and cable without a thermostat can overheat substrate and cause colony deaths. Never use either without a thermostat regulating output. Good thermostats:

Pulse-proportional or proportional thermostats - provide consistent gentle output without on-off cycling that creates temperature swings
Habistat Mat Stat and similar entry-level options - affordable, suitable for single-enclosure setups
Multi-zone thermostats - useful if heating multiple enclosures in the same area

Position the thermostat probe at the warmest part of the enclosure interior - this sets the upper limit appropriately.

Installation

The critical detail many keepers get wrong:

Mount the heat mat or cable on the SIDE of the enclosure - NOT underneath
Cover roughly half the side surface with a mat, or run a cable in straight passes at least 3cm apart and never crossing itself - either way you create a gradient where one side is warmer than the other
Insulate the back of a mat - a small piece of cork or foam behind the mat reflects heat back into the enclosure rather than wasting it to the surrounding air. Never pack insulation around a cable
Position the thermostat probe inside - taped to the wall near the heat source, not in substrate
Test for 24 hours before adding animals - make sure the temperature stabilises within target range

Why side-mounted rather than underneath: Heat rises naturally. Under-substrate heating dries out the burrow layer where isopods rest and moult. Side-mounting creates a thermal gradient through the enclosure that lets animals choose their preferred zone.

Equipment to Avoid

Heat Lamps and Basking Bulbs

NOT suitable for isopod enclosures:

Desiccate enclosures rapidly through direct radiant heat
Provide problematic bright light exposure for nocturnal/crepuscular isopods
Create dangerous hot spots
Designed for reptile basking, not for terrestrial invertebrates

Ceramic Heat Emitters (CHEs)

Same issues as heat lamps without the light. CHEs are designed for large reptile vivariums where the goal is high-output radiant heat. Inappropriate for typical isopod tubs:

Too much heat output for small enclosed spaces
Too much desiccation
Overkill for the modest temperature increases isopod keeping requires
Energy-inefficient for small enclosure heating

Running Heat Cable Under the Substrate

Same drying problem as under-substrate heat mats. Run cable along the side of the tub or the back of the shelf, never underneath.

Unbranded Cheap Heat Mats

The cheapest options on online marketplaces can be dangerous. Quality control on unbranded mats is variable; some develop hot spots or fail entirely. The modest price difference between reputable brands and unbranded options isn't worth the risk to a valuable colony.

Multi-Enclosure Setups

If you keep multiple isopod species or scale up your collection, a heat mat per enclosure becomes expensive and complicated. Better approaches:

Shelving Unit with Heat Cable

Run a heat cable along the back of a shelving unit, controlled by one thermostat, with the probe against the warmest tub on the run rather than a middle one. Elegant solution that maintains consistent warmth across multiple enclosures with one heat source.

Heated Display Cabinet

More expensive but the dedicated reptile/invertebrate display cabinets (Vivexotic, Reptizoo, etc.) include integrated heating that's designed for multiple enclosures.

Insulated Room or Cupboard

The cheapest large-scale option - dedicate a small room or cupboard to isopod keeping, heat the whole space with a single low-wattage tube heater or oil-filled radiator on a thermostat. All enclosures stay warm without individual heating.

Temperature Monitoring

You can't manage what you don't measure. Get a thermometer for each enclosure or shelving unit:

Digital probe thermometers - accurate, affordable, easy to position
Min/max thermometers - show overnight low and afternoon high; useful for identifying temperature instability
Combined temperature/humidity meters (hygrometer-thermometers) - convenient for monitoring both
Infrared thermometer guns - useful for spot-checking enclosure surfaces and identifying hot spots near the heat source

Position thermometer probes mid-height in the enclosure, away from direct contact with the heat source. The reading you want is the average enclosure temperature, not the hot spot.

Troubleshooting Common Heating Problems

Enclosure Drying Out Too Fast

Common with new heat setups. Solutions:

Reduce thermostat setting (often the heat mat is set warmer than needed)
Reduce mat surface area or coverage
Increase misting frequency
Add more leaf litter for humidity buffering
Check for excessive ventilation; some sealing may help

Substrate Hot Spots

If you see localised dry patches or signs of stress in specific areas, your heat mat is probably creating a hot spot. Solutions:

Move the thermostat probe closer to the hot spot to limit the temperature there
Add an insulating layer between the heat mat and the enclosure wall
Replace the heat mat if it's old or unbranded (quality issues)

Temperature Not Maintaining

If the enclosure isn't reaching target temperature:

Check if the heat mat is rated appropriately for the enclosure size (too small a mat for too large an enclosure)
Check if the room ambient is too cold for the mat to compensate (a 7W mat won't heat an enclosure in a 5°C room)
Check for cold air infiltration (drafts, poor ventilation seal)
Consider insulating the enclosure exterior

Thermostat Cycling Causing Temperature Swings

If your thermostat is on-off cycling rather than maintaining steady warmth, the temperature swings can stress isopods. Solutions:

Upgrade to a pulse-proportional or proportional thermostat
Reduce heat mat wattage if it's significantly oversized
Check the probe positioning - improper placement causes wider cycling

Seasonal Management for UK Keepers

Winter (November-March)

Central heating dries enclosures faster than other seasons. Increase misting frequency. Watch for overnight temperature drops when heating switches off - supplementary heating becomes more important for Cubaris and Dwarf Whites. A heated English home averages about 19°C through the heating season, and 18.1°C in December.

Summer (June-August)

UK summer brings less central heating but watch for heatwaves. Direct sun on enclosures becomes dangerous. During heatwave periods (sustained 28°C+ ambient), consider:

Switch off heat mats or cable temporarily
Move enclosures to the coolest room (often north-facing)
Keep blinds closed during the day
Avoid opening enclosures during peak heat

Transition Periods (Spring/Autumn)

The trickiest seasons for temperature management. Heating settings need adjustment as ambient temperatures change. Monitor more carefully during these periods and adjust thermostats as needed.

The Honest Bottom Line

For most UK isopod keepers, the heating equation is simple:

UK natives, most Mediterranean Armadillidium and the cooler Spanish Porcellio: No heating needed - a heated UK room is fine
Dairy Cows, Powders, Clowns and the warmer Spanish Porcellio: They tolerate a heated room; additional heat from autumn to spring keeps them breeding well
Cubaris: A side-mounted mat or cable on a thermostat - that's the entire setup
Ardentiella: No heat mat or cable; a heated room is enough. Ventilation and a genuine humidity gradient are what this genus needs
Multiple species: Shelving with heat cable, or dedicated heated room/cabinet

Avoid the complicated alternatives (CHEs, heat lamps, under-substrate heating). Use reputable brands. Always thermostat. Position the heat source on the side or behind to create a gradient. Monitor with a thermometer. That's all you need.

For setup essentials including thermostats and heating accessories, browse our accessories collection. For species-specific temperature ranges, see our temperature range guide, linked above. For broader new keeper guidance, see our first isopods guide.

Get temperature stability right and the rest of isopod husbandry becomes easier. Most colonies that "mysteriously" decline turn out to have had temperature problems somewhere along the timeline - usually heating failure, thermostat failure, or seasonal drift. Steady, species-appropriate temperatures make the difference.