Domino Cockroach Care Guide: What You Are Actually Buying

Quick answer: Domino cockroaches are black insects with seven white spots, about 2 to 3cm long, from the scrub country of southern India. They do not fly and they do not bite. Adults can climb glass but nymphs cannot. Keep them warm, at 26 to 29°C if you want them to breed, on a deep substrate that is damp underneath and dry on top, with dead hardwood leaves as the main food rather than as decoration. They are undemanding to keep alive and genuinely slow to breed. Two things most care sheets get wrong are covered below: what species you are actually buying, and the mimicry story.

This is one of the best-looking insects in the hobby and one of the most misdescribed. Almost everything written about it online traces back to two sources, one of which is a dead amateur webpage. What follows separates what has been published from what has been repeated.

You are probably not buying Therea petiveriana

The Domino has been sold as Therea petiveriana for decades, and that is what our own listing still says. It is likely wrong.

In 2009 a second species, Therea bernhardti, was described, and the view that the animal in culture is that one rather than petiveriana has gradually taken hold. The largest American breeder has retroactively relabelled its entire back catalogue, stating plainly that all stock previously sold as petiveriana should be read as bernhardti. Two UK sellers have already switched. The separating character is the hindwing: petiveriana has large yellowish hindwings and rounder spots, bernhardti short black ones and more angular spots.

Worth saying that not everyone accepts the split. One long-standing hobby forum administrator suspects bernhardti was erected on colour pattern rather than genitalia and may not stand. Both names are currently valid. But the honest position for a UK shop is that the animal in the trade is more likely bernhardti, that we cannot verify which we hold without examining wings, and that the care is identical either way. Nobody else in this country is telling you that.

Two related names you will meet. The Question Mark cockroach is Therea olegrandjeani, also black and white despite what some listings imply. The orange one is Therea regularis, and freshly moulted adults show white spots for a few days before the orange comes through, which catches people out. Do not house two Therea species together.

The mimicry story is not evidence

You will read everywhere that the spotted pattern is Batesian mimicry of Anthia sexguttata, a ground beetle that sprays formic acid. It is a nice story and there is no published support for it.

The claim on Wikipedia, which is where the whole trade copied it from, rests on a single citation to a hobbyist beetle website that no longer exists. The article's other sixteen references are real peer-reviewed papers and not one of them is cited for the mimicry. The beetle's own page makes no reciprocal claim. And the one published study of this cockroach's defensive chemistry, from 2002, found that the glandular secretion works as an alarm pheromone for other cockroaches rather than as anything aimed at a predator, which is exactly the paper that would have raised mimicry had it been credible.

There are also two awkward details. The beetle has six spots and the cockroach's own vernacular name is the seven-spotted roach. The beetle is around 4cm and the roach is 2 to 3cm. None of that disproves mimicry, since Batesian mimics are often rough copies, but nobody has run a predator trial, tested it comparatively, or even published that the two animals live in the same places. Treat it as an appealing hypothesis rather than a fact, and be sceptical of any shop that states it flatly. Ours did.

What they actually do

The published biology is better than the hobby lore. Indian work from 1978 describes this as a fossorial, crepuscular, seasonal and univoltine animal of South Indian scrub jungle, very restricted in its distribution. Unpack that and it explains the husbandry.

Fossorial means burrowing, and nymphs in particular live underground. Crepuscular means active at dusk rather than by day or deep night, though captive keepers report plenty of daytime surface activity. Univoltine means one generation a year in the wild, timed to the summer rains, and that is the real reason this species is slow. It is not a failure of your setup.

Adults climb smooth surfaces including glass; nymphs cannot. They do not fly, they do not bite, and they have no urticating hairs. Nymphs look nothing like the adults, being plain brown and unmarked, and the pattern only appears at the final moult, so if you buy nymphs expect a drab insect for a while.

Setting them up

Despite the family being called the sand cockroaches, do not use sand. That name comes from desert genera, not this one, and experienced keepers report abrasive sand damaging the cuticle and causing water loss. Use coir, soil or peat with dead hardwood leaf litter on top, around 5 to 8cm deep.

Get the moisture right and everything else follows. Every experienced breeder describes a gradient rather than a percentage: substrate damp underneath, dry on the surface, air on the dry side, and the animals sit in the band between. The reason this matters more than it sounds is that oothecae will not hatch in a dry zone. Females deposit them into moist substrate in the wild, and a colony that never produces young is very often a colony laying into substrate that is too dry.

Temperature sets the pace, and the difference is dramatic. Keeper reports line up cleanly: below about 21°C an animal takes over two years to reach adulthood, at 24°C around fifteen months, and at 27 to 29°C under a year. UK room temperature will keep them alive indefinitely. It will not breed them at any useful rate.

Feeding is where the shops have it backwards. The staple is dead hardwood leaf litter, and keepers who run them without it report animals starving despite other food being available. Fruit and vegetables are the extra, not the base, and some keepers report theirs ignoring produce entirely. Add protein through fish flake or dry dog food, since underfed colonies have been seen chewing each other's wings. Ventilation should be moderate to high, because a stagnant humid box gets mouldy.

Frequently asked questions

Do Domino cockroaches bite?

No. They have no defensive bite, no sting and no irritating hairs. Their only chemistry is a secretion that alarms other cockroaches rather than deterring anything larger.

Can they climb glass or fly?

Adults climb smooth surfaces, nymphs cannot, and none of them fly. A sealed lid is still needed for an adult colony.

Are Domino cockroaches good for beginners?

To keep, yes. To breed, less so. They are hardy and forgiving but slow, and a beginner expecting quick numbers will think something is wrong when nothing is. Our beginner cockroach guide compares the options.

Why is my colony not breeding?

Most likely too cold, or the substrate is too dry for the egg cases to hatch. Raise the warm end into the high twenties and keep the lower substrate layer damp, then wait, because the lag is measured in months.

Are they legal in the UK?

Yes, and no licence is needed. Section 14 of the 1981 Wildlife and Countryside Act makes it an offence to let any non-native animal loose or to let one get out, which makes the lid on an adult colony your legal problem as well as your practical one.

Where to go next

If the slowness does not put you off, our Domino cockroaches are captive-bred. For something that grows faster and handles more readily, the Madagascar hisser is the obvious alternative and has its own guide. The Simandoa Cave Roach, which survives only in captivity, is the other one worth a look, and the rest sit in our cockroach range.