Pogonomyrmex barbatus
(Giant Harvester Ant)
Care Sheet

What is Pogonomyrmex barbatus?

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Pogonomyrmex barbatus is the red harvester ant, a large orange or red seed-harvesting ant from the southwestern United States and northern Mexico. Workers run 5 to 9mm with a matte red head and mesosoma and a shinier gaster, and queens are 10 to 13mm. They're bigger (and tend to grow faster) than the more commonly kept Western Harvester, Pogonomyrmex occidentalis.

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The genus name means "bearded ant," after the psammophore, a basket of stiff hairs under the head used for carrying loads of sand and seed. You'll watch them use it constantly.

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This is also one of the most thoroughly studied ants in the world, which means we know things about how your colony will behave that simply aren't known for most species. More on that below.

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You can find Pogonomyrmex barbatus for sale in the US here.

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How to identify Pogonomyrmex barbatus

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Large, red to orange, and aggressive. The head and mesosoma are matte, the gaster shinier, and the whole ant is coarsely sculptured. Mackay and Mackay (2002) describes them as extremely pugnacious with a very painful sting, which is accurate on both counts.

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They're monomorphic, meaning there's no separate soldier caste. Workers vary somewhat in size but they're all the same caste.

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Where is Pogonomyrmex barbatus found?

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Across the southwestern US and into northern Mexico, in desert grassland and arid shrubland. They prefer open ground with little plant cover, and you can spot an established colony from a distance by the cleared disc around the nest entrance, often decorated with small pebbles and discarded seed husks!

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We can legally ship this species to Arizona, Arkansas, Colorado, Kansas, Louisiana, New Mexico, Oklahoma, Texas, and Utah. 

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Nests go deep. Gordon's videoscope work inside active nests found an entrance chamber surrounded by one to six adjacent chambers, with two or three tunnels leading down to strings of widely spaced chambers reaching one to two meters below the surface. Older, larger colonies have more nest entrances feeding into a single entrance chamber than younger ones do (Gordon 2024).

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Is Pogonomyrmex barbatus good for beginners?

 

This species is an amazing beginner species, as long as you're able to give them some heat! They grow quickly and steadily, have a very simple diet, and are large, agile ants that tend to figure out a setup easily. The only downside is they sting, but this can be solved by having a contained setup and not physically handling the ants (which is not at all necessary). 

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When does Pogonomyrmex barbatus fly?

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Mating flights are triggered by the summer monsoon rains, generally July through September. 

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Founding and the queen

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Pogonomyrmex barbatus queens are fully claustral. She seals herself in and raises the first workers entirely from her own body reserves. Although they can benefit from a tiny bit of seeds in founding, it isn't necessary. 

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The species is monogynous and founds on their own. One queen per tube, one queen per colony.

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First workers arrive in roughly 3 to 5 weeks at good temperatures, and they'll be noticeably smaller than later workers. The 2nd and 3rd generations are often notably larger than the nanitics, which is normal, so don't worry!

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Growth rate and colony size

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Brood development takes 3 to 5 weeks depending on how well they're heated and fed. A well-heated, well-fed colony reaches into the hundreds or 1000+ of workers within the first year, and roughly 1000-3000 by year two. They seem to grow much faster with good conditions in captivity than in the wild. Overall, this is a very fast-growing species!

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Mature colonies in the wild get to around 10,000 workers, and they take their time about it. In captivity, we can grow them much faster. More about this below!

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What 38 years of watching wild colonies tells us

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Most of what gets written about any ant species comes from a handful of studies and a lot of repetition. Pogonomyrmex barbatus, however, is studied on another level! Deborah Gordon has run a long-term study of a wild population near Rodeo, New Mexico since 1988, monitoring roughly 300 colonies a year and following around 1,500 colonies across their entire lifespans (Gordon 2024). Nearly four decades of annual censuses on the same patch of desert.

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A colony is as old as its queen. Wild colonies live 20 to 30 years, and that span is exactly the lifespan of the founding queen (Gordon and Kulig 1998; Gordon 2024). Individual workers live only about a year in the wild, so if you think about it, the colony is really just the queen! The queen in your tube could still be laying eggs and at the head of her empire when your car is scrap.

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In the wild, they don't mature for four or five years. A colony doesn't begin producing reproductives until it's four or five years old (Gordon 1995; Ingram et al. 2013). Everything before that is building up the colony large enough to do so. In captivity, we can achieve alates a good bit earlier since we can provide the ants so much more resources. It's always an achievement when you raise a colony to get alates!

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Colonies settle down as they age. Gordon (2024) found that a colony's collective behavior becomes measurably more stable and more consistent as it grows older and larger, because there are more ants participating in the interactions that regulate it. A young colony is erratic, with activity that can spike, then it stops. Foraging is inconsistent day to day. 

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There's a related finding that explains why a harvester colony sometimes just sits there. Gordon (2013) found that colonies differ in how sharply they cut back foraging on dry days, and the ones that hold back the most, sacrificing food to conserve water, have the highest lifetime reproductive success. Restraint pays! A follow-up confirmed that individual colonies stay consistent in this from one year to the next (Gordon et al. 2023).

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You won't be running drought conditions in your outworld, but the practical version is worth keeping in mind: foraging activity in this species is a decision responding to conditions, not a readout of colony health. A quiet colony may be reading its environment rather than struggling.

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Temperature and humidity

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This species requires heat, and this is where most keepers fail with it.

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Keep the nest between 88 and 95°F, with a gradient so the colony can choose. Pogonomyrmex barbatus will not grow at room temperature. They don't just grow slowly at 72°F, they go into diapause and stop growth altogether. If you wait long enough, workers will die out with no replacement, and the colony fizzles.

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If you take one thing from this sheet, it should be that. A heat cable or mat is not optional equipment for this species, and sometimes, just having it touching the nest is not enough. They need it HOT. Don't cook them, but most of the nest should be in the high 80s at least for growth.

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For humidity, they're a desert ant and they want some dry areas. A nest with a significant area being humid and another chunk being dry is a good idea, especially for dividing between brood (which prefers humidity) storage, and seed storage (the ants keep seeds dry, to keep them from germinating). 

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Don't ever let them get near freezing if you can help it.

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Do Pogonomyrmex barbatus need hibernation?

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Usually not, they grow year round and you're better off keeping them warm and productive.

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If a colony does appear to want one, cool them to room temperature or slightly below for three to five weeks, keep them well stocked with seeds through it, nest hydrated, and don't take them anywhere near freezing. Then warm them back up.

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Choosing a nest

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These ants want a nest they can grip onto, not plastic or 3D printed floors. Ultracal or Hydrostone type nests with chambers and water towers tend to work. Aside from that, they aren't very picky!

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Don't move them into a nest until they can fill up about half of it at least. They'll store seeds in the dry part, and if there isn't a good spot to store seeds, they'll just keep them piled in the outworld. 

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On the sting: This is a species where outworld security matters for your sake, not just theirs. The sting is painful and Pogonomyrmex venom is among the most potent of any insect by weight. Use a barrier, keep the lid on, and don't get casual about reaching into the outworld. If you know you react badly to stings, keep a different genus. The workers are generally relaxed and slow to sting and there isn't much reason to be handling them, but it's always possible to be surprised.

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Feeding Pogonomyrmex barbatus

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Seeds first, always! In the wild, more than 90% of their diet is seed. Keep a standing supply in the nest rather than offering it occasionally, because they store it and mill it into what keepers call ant bread. This is part of why this species is so easy and yet so fun: their feeding is so simple!

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Kentucky Bluegrass and Dandelion tend to be favorites. A varied mix works better than a single seed type. They'll eat or store what they want, and the seeds they're more picky about will be thrown into the trash pile. Generally, as colonies get older, they get less and less picky.

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Protein still helps. Fruit flies, crickets, and mealworms all get taken, and protein can augment brood production even in a species this granivorous. Offer it at least bi-weekly, more often if you're pushing growth. If they deny it, slow down on it and make sure not to let grain mites establish. Keep a well-ventilated outworld.

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Liquid sugars are optional. They'll take them and it often does no harm, but in some cases the workers may get sticky feet or it creates a mess in the outworld. Generally, I avoid it. They get their carbs from seeds, so unnecessary mess is something I don't want to create.

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Make sure there's always plenty of fresh seeds stored or available, and even then, try to add new fresh seeds into their setup every few days/weeks to make sure they aren't hungry.

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Remove uneaten protein within 16 to 24 hours to avoid mold and mites. Seed can stay, but seed 'husks' can also be a home for mites. In general, remove trash.

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Quick summary

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Heat them to 88 to 95°F with a gradient and don't compromise on it, keep seeds in the nest at all times, offer protein often, keep it partially humid and partially dry, and secure their outworld because the sting can be rough. Skip diapause. This species is super fun, enjoy them!

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Common questions

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Do Pogonomyrmex barbatus need heat? Yes, way more than most species. They're used to the hot desert. Keep the nest between 88 and 95°F with a gradient. At room temperature, they enter diapause and stop growing entirely.

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Does Pogonomyrmex barbatus sting? Yes, it's painful. Pogonomyrmex venom is among the most potent of any insect by weight. Use a barrier, keep the outworld closed, and don't handle the ants directly.

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How big do Pogonomyrmex barbatus colonies get? Several hundred or 1000+ workers in the first year and a couple thousand by year two in good conditions. Wild colonies reach around 10,000 workers and live 20 to 30 years (Gordon 2024).

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How long do Pogonomyrmex barbatus queens live? 20 to 30 years in the wild, which is the full lifespan of the colony. Workers live about a year in the wild.

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Why is my barbatus colony growing slowly? Check the heat first, since this species stops entirely below its temperature range. Beyond that, remember that wild colonies don't reach maturity until four or five years old (Gordon 1995; Ingram et al. 2013). A colony at a few hundred workers after a year is on track, though might grow faster with more heat or more food, since captive colonies can often eclipse 1000 workers by the full 1-year mark.

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Do Pogonomyrmex barbatus need hibernation? No. They grow year round. If a colony seems to want a rest, three to five weeks at room temperature or slightly cooler is enough, with seeds available throughout. Re-warm them and they should begin growing again.

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What do Pogonomyrmex barbatus eat? Seeds, primarily. More than 90% of the wild diet is seed. Keep a standing, large supply in the nest and add insect protein alongside fresh seeds often.

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References

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Gordon, D.M. (1995). The development of an ant colony's foraging range. Animal Behaviour 49: 649-659.

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Gordon, D.M. (2013). The rewards of restraint in the collective regulation of foraging by harvester ant colonies. Nature 498: 91-93.

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Gordon, D.M. (2024). The life history of harvester ant colonies. Philosophical Transactions of the Royal Society B 379: 20230332.

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Gordon, D.M. and Kulig, A.W. (1998). The effect of neighbours on the mortality of harvester ant colonies. Journal of Animal Ecology 67: 141-148.

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Gordon, D.M., Steiner, E., Das, B., and Walker, N.S. (2023). Harvester ant colonies differ in collective behavioural plasticity to regulate water loss. Royal Society Open Science 10: 230726.

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Ingram, K.K., Pilko, A., Heer, J., and Gordon, D.M. (2013). Colony life history and lifetime reproductive success of red harvester ant colonies. Journal of Animal Ecology 82: 540-550.

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Mackay, W.P. and Mackay, E.E. (2002). The Ants of New Mexico (Hymenoptera: Formicidae). Edwin Mellen Press.

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Smith, C.D., Zimin, A., Holt, C., et al. (2011). Draft genome of the red harvester ant Pogonomyrmex barbatus. Proceedings of the National Academy of Sciences 108: 5667-5672.

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Related: Pogonomyrmex occidentalis care · All care sheets

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To buy this species from us, see the product page.