Argentine Harvester Ant

Pogonomyrmex cunicularius

Argentine Harvester Ant (Pogonomyrmex cunicularius): Most Lethal Venom in Schmidt's List

The Argentine Harvester Ant (Pogonomyrmex cunicularius) is a tan-orange ant of the Argentine and Uruguayan lowlands with the most lethal venom in Justin Schmidt's 2019 list of 90 stinging insects.

Schmidt pain rating
3 out of 4; pain lasting 12 hours or more
Venom
LD50 0.088 mg/kg in mice, the most lethal of 90 stinging insects in Schmidt's 2019 list
Look
Tan-orange to tan-red all over, glossy first gaster segment, long legs
Range
Eastern Argentina and Uruguay, east and north of the Río Paraná, 20–90 m
Colony
Probably 500 to over 1,000 workers and over 100 wingless queens
Conservation
Not evaluated by the IUCN; appears rare and fragmented

Habitat & range

The Argentine Harvester Ant, *Pogonomyrmex cunicularius* (Mayr, 1887), is a lowland species of eastern Argentina and Uruguay, found at elevations of 20 to 90 m. It is only known east and north of the Río Paraná, in the Espinal, Uruguayan Savanna and Humid Pampas ecoregions. Argentine Harvester Ant appears as an Insecta creature card in Wilder TCG.

How to recognise it

Workers are one colour all over, tannish-orange to tannish-red, with yellowish hairs. The head and thorax are sculptured with fine ridges, while the first segment of the gaster is smooth and strongly shining. The legs are long, the propodeum carries a pair of moderately long spines, and like other harvester ants it has a psammophore, here poorly developed, made of hairs under the head. Its petiole node is broadly rounded in profile, which helps separate it from close relatives.

Colony life

Nests usually have a tumulus of pebbles up to 25 cm across around an entrance up to 2–3 cm wide. Colonies probably contain 500 to more than 1,000 workers and can produce more than 100 wingless (ergatoid) queens plus numerous males. Workers forage alone and can travel more than 25 m from the nest. Winged males and queens have been found in nests from 13 December to 13 February, so mating takes place in the southern summer.

The sting and venom

Justin O. Schmidt rated the sting a 3 on his 4-point scale and described it as: "A ferocious pang lasting 12 hours or more. Flesh-eating bacteria dissolve your muscles, one by precious one." (Schmidt, *The Sting of the Wild*, Johns Hopkins University Press, 2016). In his 2019 paper in *Toxins*, Schmidt listed venom lethalities for 90 stinging insects in 50 genera. The Argentine harvester ant's venom had the lowest LD50 of all, 0.088 mg/kg when injected into mice, making it the most lethal on the list, ahead of the North American harvester ants (0.12 mg/kg and up) and over 30 times as lethal as honey bee venom (2.8 mg/kg).

A name in the pain index

Schmidt's pain index lists this ant as *Ephebomyrmex cunicularis*. *Ephebomyrmex* is an old genus name that is now treated as a synonym of *Pogonomyrmex*, and the accepted spelling of the species name is *cunicularius*. The species was described by Gustav Mayr in 1887; *Pogonomyrmex brevispinus* Santschi, 1931 is a junior synonym.

Conservation

*Pogonomyrmex cunicularius* has not been evaluated for the IUCN Red List. Ant specialist Robert Johnson noted in 2015 that it appears to be rare, with very fragmented populations that likely result from intense and widespread agricultural use over most of its historic range.

Fun facts about Argentine Harvester Ant

  • Its venom is the most lethal in Justin Schmidt's 2019 list of venom lethalities for 90 stinging insects: an LD50 of 0.088 mg/kg in mice, over 30 times as lethal as honey bee venom (2.8 mg/kg).
  • Its queens are wingless (ergatoid), and a colony can produce more than 100 of them.
  • Because its queens cannot fly, the very wide Río Paraná may act as a barrier to the species spreading west.
  • Workers forage alone and can travel more than 25 m from the nest.
  • Schmidt's pain index lists it as "Ephebomyrmex cunicularis", an old genus name and a misspelling of cunicularius.

Argentine Harvester Ant vs Maricopa Harvester Ant

The Argentine harvester ant's even more lethal venom wins this card battle.

There is no record of these two meeting: the Argentine harvester ant lives in the lowlands of Argentina and Uruguay, the Maricopa harvester ant in the American Southwest. This is a Wilder comparison of two harvester ants with famously toxic venom. Schmidt rated both stings 3, and in his 2019 lethality table the Argentine harvester ant came out on top (LD50 0.088 mg/kg in mice against the Maricopa's 0.12 mg/kg).

Read more about Maricopa Harvester Ant.

Common questions about Argentine Harvester Ant

How painful is an Argentine harvester ant sting?

Justin Schmidt rated it 3 on his 4-point scale and wrote: "A ferocious pang lasting 12 hours or more. Flesh-eating bacteria dissolve your muscles, one by precious one." (The Sting of the Wild, 2016; Schmidt sting pain index).

Does the Argentine harvester ant have the most toxic venom?

In Justin Schmidt's 2019 list of venom lethalities for 90 stinging insects, it was the most lethal: an LD50 of 0.088 mg/kg in mice, ahead of the Maricopa harvester ant's 0.12 mg/kg and over 30 times as lethal as honey bee venom (Schmidt 2019, Toxins).

Where does the Argentine harvester ant live?

In the lowlands of eastern Argentina and Uruguay, east and north of the Río Paraná, at 20 to 90 m elevation, in the Espinal, Uruguayan Savanna and Humid Pampas ecoregions (AntWiki, citing Johnson 2015).

What is Ephebomyrmex cunicularis?

It is the name Schmidt's pain index uses for this ant. Ephebomyrmex is an old genus name now treated as a synonym of Pogonomyrmex (Catalogue of Life), and the accepted spelling is Pogonomyrmex cunicularius (Mayr, 1887) (AntWiki).

What does the Argentine harvester ant look like?

Workers are tannish-orange to tannish-red all over, with a smooth, strongly shining first gaster segment, long legs and yellowish hairs. Its queens are wingless (AntWiki, citing Johnson 2015).

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