Vex isopods are an undescribed woodlouse sold as Troglodillo sp. 'Vex', reported by most of the trade as Vietnamese and in the hobby only since about 2024. Ours are a warm apricot from end to end, broad and low, with a fine pale seam along every segment, and adults are reported at about 20mm. On our care panel they take a steady 22 to 26°C and are rated Hard. Sellers disagree about almost everything else, humidity most of all, so the setup we suggest is a moisture gradient with good airflow: a damp end, a distinctly drier end, and a colony left to choose. Expect a slow start to breeding. Our Vex isopods are captive-bred.
What a Vex is, and what it is not
Troglodillo is a real and fairly old genus. Jackson named it in 1937, it sits in the family Armadillidae, and it is not a recent split from Cubaris. Three species have been formally described: T. emarginatus from a cave in Lampang, northern Thailand, T. rotundatus from Guilin in southern China, and T. latellai. Two of the three are known from caves.
The Vex is not one of them. It has no scientific description, so its place in Troglodillo is the hobby's attribution, based on how it looks, and not a published decision. We have found nothing published that ties it to a cave either. If it is ever described, the name on the label may change, as it has for several animals in this corner of the hobby.
Where it comes from is the trade's account too. A Dutch breeder gives Vietnam and says it was found in August 2024. A European shop gives China. Our panel says Vietnam, marked as the trade's report, because we have found no published collecting locality to settle it.
Sellers do not agree on what it looks like
This is the strangest thing about the Vex. Read four sellers' pages and no two agree. One describes reduced pigmentation and a ghostly look, the way cave isopods are often written up. An American shop describes a dark, textured shell. The Dutch breeder describes a dark ring round the back with a lighter centre and a bright orange skirt. And the sizes run from 8 to 12mm on one European page to 20mm on the Dutch breeder's, who calls it the largest known Troglodillo.
Some of that text may come from generic care templates, or more than one animal may be moving under the same trade name. We cannot tell which from here. What we can tell you is what ours look like.
Ours are apricot to soft orange all over, with a glossy, slightly translucent shell. Each segment is edged with a fine pale line, so the animal reads as a stack of overlapping plates rather than one smooth dome. The legs and antennae are nearly white and the eyes are small and dark. The body is broad and flat: where a Rubber Ducky is tall and round, the Vex is built to press itself into a crevice. It is vividly coloured, so whatever the cave-style descriptions are about, they do not describe these.
If you buy Vex from more than one source, keep each group in its own labelled tub until you are sure they match. Mixing two different animals under one name is easy to do and slow to undo.
Setting up for a Vex
Temperature
Our panel gives 22 to 26°C. Seller figures run from 18 to 26°C at one end to 24 to 28°C at the other, and our 22 to 26°C sits in the middle of that spread. A heated English home runs at about 19°C from October to April and about 21.5°C in July and August, both below this band, so plan on gentle heat for most of the year: a heat mat or cable on a thermostat, fixed to the side of the tub and never underneath. Our guide to heating isopods explains how to fit one. Keep the tub away from radiators, windows and draughts. Steady conditions are what this group does best on, so avoid sudden swings.
Humidity: let the colony decide
Here the sources split hardest. The Dutch breeder keeps them at 50 to 60% and says they prefer it a bit drier. One shop says moderately high. Another says 80 to 90%. Our panel gives no humidity figure on purpose, because I have not kept them long enough to settle the argument, and a single number would hide it.
In practice, a gradient gets round it. Keep about a third of the tub damp, under sphagnum moss and a thick layer of leaves, and let the far end run distinctly drier. Give the tub cross-ventilation, with mesh in two opposite walls, so the damp end never turns stale; our article on ventilation and humidity covers the layout. Then watch where they sit. If the colony lives at one end week after week, that end is telling you more than any care sheet can.
Substrate and cover
Lay a good depth of flake soil, white-rotted hardwood and organic topsoil, enough for them to dig into. Leave coco coir out: it holds water well, but it is not food, and a woodlouse eats the ground it lives on. Cover the surface with hardwood leaf litter, then add bark flats and cork for crevices. A flat-bodied animal wants tight gaps to wedge under, and the Vex will spend most of the day in them.
Food and calcium
Leaf litter and rotting wood are the staple. Add small pieces of vegetable, and protein a couple of times a week; the Dutch breeder feeds protein at least twice weekly. Fish flake works. Leave cuttlebone or limestone in at all times, since every moult means hardening a new calcium carbonate shell. Lift uneaten fresh food after a day, since anything left sitting on the damp side will mould.
Breeding: slow, then steady
Know this before you buy. The Vex takes its time. The Dutch breeder reports that a new group may take a few months to produce young and then breeds steadily, mostly in the warmer months, with far fewer young in winter, and gives a lifespan of two to three years. Our own listing calls it slow even by the standards of its group. We have found no report of a fast Vex colony anywhere in the trade.
That makes stability the whole game. Hold the temperature steady, keep the gradient the same from week to week, leave calcium in, and do not dig the substrate over to look for young. Females brood their eggs in a pouch under the body, and the young come out with six pairs of legs and add the seventh as they moult; they are easy to miss in deep litter, which is another reason not to go looking.
They are mostly active at night. In a display tub, keep the light low and indirect, and expect to see less of them than you would of a Porcellio.
Which Troglodillo should you start with?
Not the Vex, if this is your first. Our panel rates it Hard, breeders report a slow start, and the care sheets still disagree on its humidity. The Sunset is a gentler way into the genus, warm orange, rated Easy and a steady breeder; our Sunset isopod care guide covers it. Soil isopods are the easy ones in the group. Once you have held a Sunset or a Cubaris colony steady through a full year, the Vex is a fine next step. Every Troglodillo we sell is on our Troglodillo page.
Frequently Asked Questions
What are Vex isopods?
An undescribed woodlouse sold as Troglodillo sp. 'Vex'. The genus is a hobby attribution, and the trade reports the animal from Vietnam. Ours are apricot to soft orange, broad and flat, with pale-edged segments.
How big do Vex isopods get?
About 20mm on our care panel, the same figure the Dutch breeder gives. One European shop gives 8 to 12mm, which may describe a different animal sold under the same name. We have found no published measurement.
What humidity do Vex isopods need?
Sources range from 50 to 60% up to 80 to 90%. Keep a damp third and a drier rest of the tub with good cross-ventilation, and let the colony show you which end it prefers.
Do Vex isopods need heat?
In most British homes, yes, for most of the year. Hold them at 22 to 26°C with a heat mat or cable on a thermostat, fixed to the side of the tub and never underneath.
Are Vex isopods cave isopods?
Two of the three described Troglodillo species are known from caves, but we have found nothing published that ties the Vex to one. Ours are richly coloured, not pale or eyeless.
Are Vex isopods good for beginners?
No. They breed slowly, the care information conflicts, and our panel rates them Hard. Start with an easier species and come back to the Vex once you have kept a colony steady for a year.
Where to start
Build the tub first: heat on its thermostat, the damp third made, the vents cut. Let it run for a week so the temperature and the gradient hold, then add the animals, and leave them alone while they settle.
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