Two of the display cockroaches we keep wear the same piece of jewellery. Adult males of both carry a pair of yellow-orange spots high on the pronotum, sitting just behind the head against a dark body, and looking for all the world like a pair of headlights switched on in the dark. They are the Headlight Cockroach, Lucihormetica verrucosa, and the Glowspot Cockroach, Lucihormetica subcincta.
People buy one and then wonder whether the other is worth having as well, or buy the wrong one for what they actually wanted. This is the comparison, plus the bit of the story that gets told wrong more often than it gets told right.
First, the name. They do not glow.
Both species are widely described as bioluminescent. Neither is, and it is worth understanding where that came from, because the myth is stubborn.
In 2012 a paper in Naturwissenschaften by Vrsansky and colleagues proposed that a related species, Lucihormetica luckae, produced its own light, and suggested the spots were mimicking bioluminescent click beetles. It was a striking idea and it travelled a long way. The trouble is that it was never substantiated, and when Greven and Zwanzig examined the pronotum of L. verrucosa in detail in 2013, they found no light-producing organs at all. What they found instead was a pad of enlarged fat body cells packed with carotenoids, sitting under a thin translucent cuticle. Colour, in other words, not light.
So no amount of feeding glowing mushrooms, adding bacteria or sitting in the dark is going to switch anything on. If you see that advice, it is chasing something that does not exist.
What you can actually do with the spots
Here is the part that survives, and it is more fun than the myth.
The spots fluoresce. They do not generate light, but they do absorb ultraviolet and re-emit it as visible light, so under a UV torch they light up in a way they simply do not under a room lamp. Beckert, Greven and Lunau looked at this in 2017 and found something useful alongside it: both the UV reflection and the autofluorescence are affected by carotenoids in the diet.
Which means two practical things. A 395nm UV torch is genuinely worth owning if you keep these, and it costs almost nothing. And a carotenoid-rich diet, carrot, pumpkin, sweet potato and squash, feeds directly into how deep and how orange those spots go. You cannot make them glow. You can make them better.
Only adult males wear the spots
This catches people out, so it is worth being blunt about it. Females of both species are plain glossy dark brown with no markings at all. Nymphs of both sexes are unmarked. The males develop their spots at the final moult and not before.
So a tub of nymphs is a promise rather than a display, and it will be several months before it becomes one. If you want spots on the shelf sooner, ask for adult males when you order and we will pick them out where stock allows.
Telling the two species apart
Side by side they are easy, and the differences are more interesting than the similarities.
The Headlight has a warty, textured pronotum, which is what verrucosa means, and brown wings. It reaches roughly 4cm as an adult, and unusually for insects the males run slightly smaller than the females. It comes from Venezuela and Colombia.
The Glowspot carries the same spots on a smooth shield with none of that warty texture, and its wings are pale ivory rather than brown, which reads very differently across a tank. The nymphs are striking in their own right, shiny bodied with orange heads. It comes from Colombia.
The clearest practical difference is not appearance at all, it is pace. The Headlight breeds readily. The Glowspot is slow, taking well over a year to reach maturity and building numbers gently rather than in waves. If you want a colony that establishes and then quietly gets on with it, that is the Headlight. If you are happy to keep something ticking over for the pleasure of watching it, the Glowspot is the more contemplative animal, and it is calmer and more deliberate in the tank too.
Which one should you buy?
If you are buying your first of the two, buy the Headlight. It breeds sooner, it is more forgiving of a colony finding its feet, and it gives you the effect you came for faster.
If you already keep the Headlight, the Glowspot earns its place rather than repeating it. Ivory wings against a smooth pronotum, orange-headed nymphs and a slower temperament make it a genuinely different tank rather than a second copy of the first.
If you want both, keep them separately. They are closely related enough that the question of hybrids comes up in the hobby, and there is no good reason to find out on your shelf.
Warmth is the real commitment in a UK home
Both species want somewhere around 24 to 28°C. That is above what a British house sits at for most of the year, so this is not a species you can keep on room temperature alone and hope for the best. Some added heat is part of the deal.
A low-wattage mat on a thermostat, fixed to the side of the enclosure rather than underneath it, is the arrangement that works. Side-mounting matters because both species burrow and spend much of the day under the surface, and a mat beneath the tub heats exactly the layer they retreat into. Aim for a warm end and let the far side of the enclosure run cooler, so the animals can choose.
Humidity wants to sit fairly high, roughly 60 to 80 per cent, which in practice means damp substrate rather than a wet tank and a spray when the surface dries out.
Setting them up
Give them a deep layer of substrate they can burrow into, because that is where they will spend most of the daylight hours. We use flake soil as the base, topped with bark hides and a generous covering of leaf litter such as our magnolia leaves, which they shelter under and slowly graze on.
The Glowspot does something worth knowing about here: it holds semi-permanent burrows and will drag leaves down into them. If you see an established burrow area when you are tidying, leave it alone.
Adults of both species climb glass and smooth plastic without difficulty, so a secure and well-ventilated lid is not optional. Neither species has any prospect of establishing outdoors in this country. They are tropical animals and a British winter would finish them, which is worth saying plainly given how nervous people are about keeping roaches at all.
Feeding
Neither of these is a feeder roach that swarms its food, so offer a little and often rather than piling it in. Vegetables and fruit make up the bulk, with a protein source such as fish flake or dried insects added now and then.
Lean on the carotenoid vegetables for the reason above. Carrot, pumpkin and sweet potato are not just food here, they are pigment, and the difference shows on the males.
Females of both species are ovoviviparous, holding their eggs internally and giving birth to live young rather than laying an egg case you can see. So a colony that looks static may not be, and nymphs tend to appear without warning.
Where they sit in a shelf of display roaches
These two belong with the calm, watchable species rather than the fast ones. The marbled Centurion Porcelain Cockroach and the soft green Cuban Cockroach are natural companions on the same shelf, and all four are handsome, undemanding and easy to sit and watch.
If you are earlier in the hobby than that, our guide to the best pet cockroaches for beginners in the UK is the place to start, and the Gyna porcelain cockroaches guide covers the marbled species in detail. The full range is in our cockroaches collection.
Every animal we send is captive-bred here, packed double-walled around a ventilated tub of damp sphagnum and posted Monday to Thursday by tracked Royal Mail, with a live arrival guarantee.
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