Diacamma viridipurpureum quezonicum - Blue Morph

Diacamma are large, fast, sharp-eyed ponerine ants that hunt alone on the floor of tropical Asian forests, and they are exceptionally aggressive towards any arthropod that crosses their path. They also have one of the strangest societies in the ant world: they have no queen. The eggs are laid by a mated worker, the gamergate, who defends her position with a method as drastic as it is effective: she mutilates her newly emerged sisters so that they can never reproduce. Diacamma viridipurpureum quezonicum, the Blue Morph from the Philippines, adds a metallic blue sheen to all this, making it one of the most striking ants you can keep.

A word of warning before we start: this subspecies is known only from its description, and almost all the science on the genus has been done with other species (D. australe, D. ceylonense, D. indicum and the Diacamma from Japan). What we describe here is the biology of the genus Diacamma, which we extrapolate to the Blue Morph because it shares the same social system; we point this out in each case.

Biology

What is a gamergate?

A gamergate is a mated worker that lays eggs and acts as the "queen" of a colony that has none. The word comes from the Greek gamos, "marriage", and ergátēs, "worker": literally, a "married worker".

In almost all ants, reproduction is the job of the queen: a special female, born with wings and with a larger, more muscular thorax for flying, who mates during the nuptial flight and founds the colony. In Diacamma that caste does not exist: Wheeler and Chapman did not find it in 1922, and nobody has found it since. All females are born as workers, and reproduction is taken over by a single mated worker per colony, usually mated with just one male.

How does a gamergate differ from a queen? In almost everything except her role:

• She has no wings and never had any, and she does not make a nuptial flight: she mates at the nest entrance.
• She does not have a queen's body: her thorax is that of a worker, and she is the same size as her nestmates. In 26 colonies of D. ceylonense, the gamergate was the only mated individual with developed ovaries, but she could not be told apart by size.
• A gamergate is made, not born: her role is not decided during larval development but in the adult, through social manipulation. What gives her away is her chemistry: the hydrocarbons on her cuticle, the "signature" ants read with their antennae, change with ovarian activity. At the genetic level the difference is tiny: in the Diacamma from Japan, very few genes separate the gamergate from the workers, mostly genes related to nutrition, and the dominant position changes their expression almost immediately.

To the naked eye, the best clue is the thorax: the gamergate is the only one that keeps her gemmae, two small appendages that are torn off all the other workers when they emerge, as we will see shortly. The colonies she rules are small to medium-sized: 30 to 300 workers in the Diacamma from Okinawa, an average of about 230 females in D. ceylonense and about 273 in the "nilgiri" form, the highest figure known for the genus.

What is the Blue Morph? A blue gladiator from the Philippines

"Blue" is the trade name under which this blue-sheened Diacamma circulates among keepers. Its scientific name is Diacamma viridipurpureum quezonicum Laciny, Pal & Zettel, 2015, a subspecies of D. viridipurpureum Emery, 1893 described from the island of Luzon, in the Philippines. The Antomas line comes from the Philippines.

Laciny, Pal and Zettel described it in 2015, as part of a revision of the Philippine Diacamma, from a series of workers collected in Quezon National Park (Atimonan, Quezon Province, Luzon), which gives it its name. The nominate form, D. viridipurpureum viridipurpureum, is known from around Manila (its type locality is Antipolo) and has a duller, polychrome sheen dominated by dark greens and purples, hence the name "green-purple". The subspecies quezonicum differs from it in details of the clypeus, eye size, the rugae of the propodeum and the process under the petiole, and in its intense blue iridescence.

It should not be confused with Diacamma caeruleum, another Philippine species described in the same work, from the island of Mindoro, which also has a strong metallic blue sheen: by colour, D. caeruleum can be told apart from almost all its relatives, but not from quezonicum, and separating them requires looking at morphology. At Antomas we also have its two "colour sisters", also from the Philippines: the Purple Morph, Diacamma excellens, and the Green Morph, D. viridipurpureum viridipurpureum. Blue, purple and green: three metallic gladiators from the same islands.

The genus Diacamma Mayr, 1862 contains about 44 valid species (Bolton, 2024), plus more than 20 subspecies, and ranges from India and southern China to southern Japan, Southeast Asia and northern Australia. The Philippines is one of its centres of diversity, with several metallic species.

In the wild, Diacamma nest in the soil, often under stones or among roots. Their nests are simple: in D. indicum, a study of 77 casts of natural nests showed that they almost always have a single entrance and a single chamber, and that only the entrance tunnel changes with the season.

A bite that decides destiny: gemmae and mutilation

All Diacamma workers are born with a pair of gemmae: two small appendages on the sides of the thorax, covered with sensory hairs and with a gland of their own. They are probably what remains of the wings: in the larvae, the wing buds degenerate almost completely, and the little that survives becomes the gemma.

When a worker leaves her cocoon, still soft and pale (a callow), the gamergate seeks her out, bites her gemmae and tears them off. That worker will never perform the sexual calling or mate: she will be sterile as a mated female for ever. Mutilation causes the nerve connections between the sensory hairs of the gemma and the central nervous system to degenerate, which would explain why the effect is irreversible.

A detail many websites get wrong: mutilation does not happen "at pupation", but to newly emerged adults. Callows do not resist a mature gamergate, but they are aggressive towards other unmutilated callows, their direct rivals.

The signal comes from the victim, and the Diacamma that does not mutilate

How does the gamergate know whom to mutilate? An ingenious experiment gave the answer. In southern India lives a form of Diacamma known as "nilgiri", close to D. ceylonense, whose gamergate does not mutilate: she keeps her monopoly through dominance and aggression alone. Researchers swapped cocoons between the two: "nilgiri" callows raised in D. ceylonense colonies were not mutilated, while D. ceylonense callows were mutilated in "nilgiri" colonies, where nobody mutilates.

Conclusion: the cues that trigger mutilation come from the victim herself, probably from her gemmae, and do not depend on the colony she grows up in. It is one of those cases where a small exception helps to understand the rule.

The succession: a new gamergate when the old one dies

Usurpation is practically impossible: while the gamergate is alive, she mutilates every newly emerged worker. But when she dies, there is nobody left to mutilate, and a callow that keeps her gemmae, usually the first to emerge, mates and takes her place. In this way the colony can outlive any of its members.

This succession has one important condition: the new gamergate needs a male, and in the wild males come from other colonies. In captivity the same can be achieved by providing a male from another colony (we explain this under "If the gamergate dies").

Sexual calling, two-day mating and a male that does not survive

A few days after emerging, the unmutilated female goes to the nest entrance and performs the "sexual calling": she releases pheromones from the metatibial gland, in her hind legs, to attract winged males from other colonies. What follows is one of the most striking things about the genus: mating can last up to two days, and when it ends, the gamergate herself and the workers kill the male and remove him. The new gamergate stays fertilised for the rest of her life with the sperm of that single male.

Double policing and males fathered by workers

Mutilated workers cannot mate, but they keep their ovaries and can lay unfertilised eggs, which in Hymenoptera always produce males. With the gamergate present they rarely do so; if the colony is left orphaned, they start laying often. To prevent this, the Diacamma from Japan has double policing: both the gamergate and the other workers watch and punish those that try to reproduce.

This policing depends on the stage of the colony. In a 2018 study, males only came from colonies of at least a hundred workers (of 56 males, 47 came from colonies of more than 100 and none from colonies of fewer than 50), and in the laboratory 58 % of the males were sons of virgin workers, not of the gamergate. When the colony is large, policing relaxes and the workers manage to slip in their own offspring.

Colonies that split: fission

Without winged queens there is no nuptial flight and no founding by a lone female. Diacamma multiply by fission: a group of workers splits off with a new gamergate and forms another colony. There are no published figures on how many workers leave in each split. In D. indicum researchers have even studied what happens when the parts of a divided colony meet again, and in the Diacamma from Japan splits and fusions have been observed in the laboratory.

Tandem moves: the follower travels with brood in tow

Diacamma do not lay pheromone trails to recruit: they do it in tandem (tandem running). A worker that knows the way leads a nestmate, who follows by touching her with her antennae. In D. indicum, when the colony moves, most females travel this way, including the gamergate, while brood and males are carried in the mandibles. And there is a trick to save trips: the follower carries a brood item in her mandibles while following the leader, so that one adult and one larva or pupa are moved in a single journey.

Leaders that choose the shortest route

The leaders of these moves are not automatons. If the target nest changes, most of them readjust their route almost without error (in an experiment with 262 leaders, the error was 1.65 %); if the main leader is removed, others replace her at the same rate; and, among several possible paths, they choose the shortest significantly more often than the others. All this in a colony of a few hundred individuals and without chemical trails: pure memory and individual orientation.

Solitary hunters faithful to their heading

Diacamma hunt alone and by day. In D. ceylonense, about 24 % of the workers are outside the nest at any moment, a proportion so stable that it can be used to estimate colony size without digging it up. Each forager goes out hunting only during one stage of her life, 9 to 23 days, and most are faithful to one direction or a narrow sector around the nest; together they cover all directions. That they navigate by sight is very likely, given their large eyes, but it has not been specifically studied.

Their main prey are termites, which make up most of the diet of D. ceylonense; D. rugosum has been described as a very effective termite predator in experimental arenas. They locate the prey, stalk it, sting it until it is paralysed and carry it to the nest; when they find a large food source, they recruit nestmates in tandem.

Feathers and corpses at the front door

One of the most curious observations about the genus was made by the naturalist Mark Moffett in 1985: some Diacamma surround their nest entrance with feathers and ant corpses. The explanation proposed is that these objects serve to collect morning dew, a source of water right by the door. It is a hypothesis, not a proven fact, and we do not know whether the Blue Morph does it; if you see something similar in your colony, we would love to see it.

A blue that is probably not a pigment

As early as 1922, Wheeler and Chapman described Diacamma workers as "large black or bronzy, more rarely beautifully metallic blue or green". In the Philippine species described in 2015, the type of sheen is even a character used to tell species apart. Nobody has studied where this sheen comes from in Diacamma, but in insects metallic blue is usually a structural colour: it is not produced by a pigment but by microscopic layers in the cuticle that reflect light like a soap bubble. That is why the blue of the Blue Morph changes with angle and light, and looks much better in sunlight or under a lamp than in dim light.

Size and morphology

Diacamma are slender yet robust ponerines, with monomorphic workers: they all have the same shape and a similar size, and the gamergate is just another worker. Features of the genus:

• Sculpture. The cuticle is covered with striae and rugae, longitudinal on the head, concentric on the pronotum and oblique on the rest of the thorax; the first gastral segment has concentric transverse striae and the rest is smooth. The pattern of this sculpture is used to distinguish species; rugosum means precisely "wrinkled".
• Petiole. A thick scale topped by a pair of sharp spines, very characteristic of the genus.
• Head. Large, convex eyes, triangular mandibles with 7 teeth and 12-segmented antennae.
• Gemmae. Two small appendages on the thorax, present in all workers at emergence and torn off in all of them except the gamergate. They are the best way to recognise her: the gamergate is the only one that keeps her gemmae.
• Sting. Functional, long and curved upwards.
• Male. Winged, yellowish brown, with very large eyes, three ocelli, reduced mandibles and 13-segmented antennae.

Colouration. Dark body with an intense metallic blue sheen which, in the Antomas line, can be seen over the whole body and changes with angle and light. It is the feature that separates the Blue Morph from the nominate form of its species, which has a duller green and purple sheen.

Approximate measurements

• Workers: 13–15 mm, based on Antomas's experience with its line
• Gamergate: 13–15 mm, the same as the workers (workers are monomorphic and the gamergate cannot be told apart by size)
• For comparison, D. viridipurpureum (nominate form), worker: 12.8–13.8 mm
• Genus Diacamma, workers: usually 8–16 mm, depending on the species
• Male (genus reference, D. rugosum jerdoni): about 10 mm

We have not found published measurements of the subspecies quezonicum available online; those of the nominate form come from the revision by Laciny, Pal and Zettel (2015).

Care in captivity

Difficulty: 3/5 – Advanced

It is not a delicate species day to day, but it has several requirements that place it at an advanced level: it needs very high and constant humidity without the nest becoming waterlogged or mouldy; it eats mainly live prey; and the colony depends on a single gamergate, who must be protected when handling the nest. Keepers' opinions range from "quite easy" to "experts only", and the consensus puts it at an intermediate level.

And it is well worth it. Watching them hunt is a spectacle: large, fast, sharp-eyed workers that locate, chase and sting their prey with exceptional aggression. You can also watch a unique social system live: the gamergate with her gemmae, tandem moves with followers carrying brood and, with luck, the emergence and mutilation of new workers. All with a blue sheen that few ants have.

Recommended parameters

• Temperature: 24–28 °C, with a gradient (one end of the setup around 28 °C and the other cooler, around 24 °C), so the colony can choose where to place the brood. This matches what keepers of the genus use.
• Nest humidity: very high, 60–80 %; at Antomas we usually work at around 70 %.
• Foraging area: somewhat drier than the nest, with a water source always available.
• Diapause: none. It stays active all year round at 24–28 °C; avoid sudden temperature changes.
• Light: keep the nest dark or covered; the foraging area can be lit. They are diurnal, highly visual hunters.

Keep a humidity gradient: a wetter zone for eggs and larvae and a slightly less humid one, so the colony can choose. Moisten little and often, never all at once: excess water brings mould and mites.

Recommended formicaria

At Antomas we recommend the Anthouse Qbik Wild range, with any of its three humidity systems: hybrid (an evaporation reservoir under a technical mesh plus a side drinking tube), evaporation (the water never touches the chambers, creating a natural humidity gradient) and standard (refillable water tube). All three work well; for the colonies we sell, the most suitable format is the Duo, and the one we recommend most is the Qbik Wild Duo P 2C Hybrid.

Qbik Wild Duo P 2C Hybrid

Qbik Wild Duo P 2C Evaporation

Qbik Wild Duo P 2C

In the foraging area, a substrate of sand with a little clay and some small stones gives a natural look and helps to hold humidity. Expand the formicarium when the colony fills almost all the space, not before: an oversized nest dries out or goes mouldy in the empty areas.

Arrival of the colony and the first weeks

At Antomas we sell colonies with a gamergate, in whatever size is available at the time. A gamergate on her own cannot found a colony: in Diacamma colonies arise by fission, so she always needs workers.

When it arrives, set it up in a quiet place, in the dark and at a stable temperature, and remove any workers that died in transit. During the first weeks avoid vibrations, strong light on the nest and opening it to look inside: these are the most common reasons for a colony to stop raising brood. To move it to a new formicarium, at Antomas we almost always do it by tipping it in: we tip the colony into the new formicarium and often force them to go inside. It is the method that works best for us.

To recognise the gamergate, look at the thorax: she is the only one that keeps her gemmae, while the other workers only show the scars. In Antomas's experience, the gamergate is very shy and elusive and never goes out to forage: do not expect to see her in the hunting area.

If the gamergate dies

It is the big worry of every Diacamma keeper, and there is a solution. When the gamergate dies, mutilation stops, and the workers that emerge from then on keep their gemmae: any of them can become the new gamergate if she mates. All she needs is a male, and it has to come from another colony: in the wild, Diacamma mate with males from neighbouring colonies.

In Antomas's experience, it works: several customers who lost their gamergate asked us for males and managed to get an unmutilated worker to mate and take over. If it happens to you, contact us and we will help. Meanwhile, keep feeding and caring for the colony as usual. And, of course, the best thing is not to lose the gamergate when handling the formicarium.

Feeding

The basis is a varied diet of protein, mainly live prey, and sugars.

Protein. Prey that is mostly live, although they also accept dead prey. At Antomas we recommend it because it is by far the most spectacular option: they are exceptionally aggressive towards other arthropods and invertebrates, and watching them locate, chase and sting their prey is the best thing about this species. Offer crickets, feeder cockroaches, flies, mealworms and other safe feeder insects, of a size they can overpower, and change the type of insect from one week to the next so they do not always eat the same thing. At Antomas we give them protein 3–5 times a week, depending on how many larvae the colony has.

Do not skimp on protein: according to keepers, a hungry colony may end up eating its own brood. Remove leftovers within 24 h: with the humidity this species needs, they go mouldy very quickly.

Sugars. They are quite fond of sugary liquids. You can offer them every 3–4 days or keep a sugar feeder ad libitum, always available, with no problem. Vary the sugar: use Anthouse Blue Sugar Nectar as the base, 4–5 times a week if you use a feeder, and another sugary liquid 1–2 times a week. For those days, at Antomas we recommend a mix of lactose-free milk with honey, which also adds some liquid protein to the diet (important: it must be lactose-free).

Water: clean water always available.

Behaviour in captivity

This is a very active species outside the nest, especially in warmth and light: the workers patrol the foraging area alone and react immediately to any prey. They are extremely aggressive towards other arthropods, and also towards ants from other colonies: do not keep them in mixed setups. Towards people, on the other hand, they are not particularly aggressive. If the colony moves, you will be able to see tandem running and followers carrying brood.

Warning signs: if the colony crowds into the warmest spot and there is hardly any brood, it usually lacks warmth or humidity; if it stops raising brood after the nest has been handled, leave it alone for a few days.

Escapes and barriers

They are not great escape artists. At Antomas we recommend a lid that fits well and is ventilated, and a large foraging area where they have room to patrol and hunt; that is usually enough. As an additional barrier you can use oil, petroleum jelly or "talcol" (talcum powder mixed with alcohol, applied as a band that leaves a layer of talc once the alcohol evaporates).

A warning: Fluon (PTFE) loses effectiveness at high humidity, and with this species humidity is always high; the barrier can fail without you noticing. If you use it, use it with a lid. Also check plugs, joints and connections: any gap is an exit for an ant of this size.

Handling and safety

Diacamma have a functional sting, but in Antomas's experience they find it quite hard to pierce the skin and are slow to sting. They are not particularly aggressive towards people: they save all their aggression for other arthropods. As with any sting, people allergic to hymenopteran stings may react, so handle them with a brush or soft tweezers, and work slowly so as not to lose the gamergate. This is an exotic species: it must never be released into the wild.

What not to do

• Let temperature or humidity go out of range, or change them suddenly.
• Overwater: a waterlogged nest brings mould and mites.
• Leave food remains for more than 24 h.
• Give too little protein or always the same insect (lack of protein can lead to brood cannibalism).
• Expand the formicarium before the colony needs it.
• Subject it to vibrations, strong light on the nest or frequent opening.
• Fail to remove dead workers after arrival.
• Handle carelessly and lose the gamergate.
• Try to merge colonies: it cannot be done, they are quite aggressive towards each other. Do not keep them with other species either.
• Rely on Fluon alone at high humidity, without a lid.

Scientific sources

This care sheet is based on the description of the subspecies, the scientific literature on the biology of the genus Diacamma, and the experience of Antomas and European keepers. Main references:

1. Laciny, A., Pal, A. & Zettel, H. (2015). Taxonomic notes on the ant genus Diacamma (Hymenoptera: Formicidae), part 1. Zeitschrift der Arbeitsgemeinschaft Österreichischer Entomologen 67: 83–136. zobodat.at
2. Peeters, C. & Higashi, S. (1989). Reproductive dominance controlled by mutilation in the queenless ant Diacamma australe. Naturwissenschaften 76: 177–180. doi:10.1007/BF00366404
3. Gronenberg, W. & Peeters, C. (1993). Central projections of the sensory hairs on the gemma of the ant Diacamma: substrate for behavioural modulation? Cell and Tissue Research. doi:10.1007/BF00333695
4. Gotoh, A., Billen, J., Hashim, R. & Ito, F. (2005). Apoptotic wing degeneration and formation of an altruism-regulating glandular appendage (gemma) in the ponerine ant Diacamma sp. from Japan. Development Genes and Evolution. doi:10.1007/s00427-004-0456-7
5. Ramaswamy, K. et al. (2004). Social mutilation in the ponerine ant Diacamma: cues originate in the victims. Insectes Sociaux 51: 410–413. doi:10.1007/s00040-004-0765-x
6. Cournault, L. & Peeters, C. (2012). Aggression regulates monogyny in non-mutilating Diacamma ants. Insectes Sociaux 59: 533–539. doi:10.1007/s00040-012-0251-9
7. Baratte, S., Cobb, M. & Peeters, C. (2006). Reproductive conflicts and mutilation in queenless Diacamma ants. Animal Behaviour 72: 305–311. doi:10.1016/j.anbehav.2005.10.025
8. Okada, Y. et al. (2017). Social dominance alters nutrition-related gene expression immediately: transcriptomic evidence from a monomorphic queenless ant. Molecular Ecology. doi:10.1111/mec.13989
9. Kikuta, N. & Tsuji, K. (1999). Queen and worker policing in the monogynous and monandrous ant, Diacamma sp. Behavioral Ecology and Sociobiology 46: 180–189. doi:10.1007/s002650050608
10. Shimoji, H. et al. (2018). Social enforcement depending on the stage of colony growth in an ant. Proceedings of the Royal Society B 285: 20172548. doi:10.1098/rspb.2017.2548
11. Kaur, R. et al. (2014). Coupled adult-brood transport augments relocation in the Indian queenless ant Diacamma indicum. Insectes Sociaux. doi:10.1007/s00040-014-0338-6
12. Mukhopadhyay et al. (2019). Path minimization in a tandem running Indian ant in the context of colony relocation. Journal of Experimental Biology. doi:10.1242/jeb.206490
13. Baidwan et al. (2024). Description of Diacamma rugosum jerdoni (Insecta: Hymenoptera) male along with two new additions to the myrmecofaunal diversity of Kerala, India. Halteres 14: 20–30. doi:10.5281/zenodo.14439664