Spiders in Argentina

What spiders live in Argentina?

Argentina runs from the subtropics to the sub-Antarctic, and its spiders change completely along the way. The humid Atlantic forest of Misiones and the dry Chaco hold a warm-climate fauna shared with Paraguay and Brazil; the Pampas around Buenos Aires are temperate open grassland; the Monte desert along the Andes is arid, and Patagonia is windy steppe. Well over a thousand spider species have been described from the country; the twelve profiled here are the ones people meet in houses and gardens.

The eye-catching web builders are orb weavers. The golden silk orb weaver strings huge yellow-tinted webs between trees in the north, the banded garden spider works open grassland, and the tiny spinybacked orbweaver, a hard white shell with red spines, hangs in northern gardens. Around buildings the southern house spider fills wall cracks with lacy sheets, while the red house spider and triangulate cobweb spider take ceiling corners.

The hunters are just as common. Lyssomanes are translucent green jumping spiders of the northeastern forests, and the gray wall jumping spider patrols sunlit walls in the warm north. Grammostola tarantulas, including the bulky Guaraní giant, walk the grasslands at dusk in the mating season.

Which Argentine spiders are dangerous?

Widow spiders. Argentina's medically important widows are native grassland species, chiefly Latrodectus mirabilis and Latrodectus corallinus. The female is black with red or orange markings and builds an untidy snare at ground level in tussock grass, vacant lots, under boards and inside abandoned machinery. Envenoming produces latrodectism: local pain spreading into muscle cramping, sweating, raised blood pressure and a board-like abdomen. Specific widow antivenom is produced in Argentina and held by hospital networks; with treatment the outlook is excellent. The introduced brown widow (Latrodectus geometricus) is now common around cities, but it is shy and injects little venom, so bites are usually mild.

The Chilean recluse. Loxosceles laeta is the single most important spider for Argentine households. It is a plain tan spider with six eyes in three pairs that lives behind wardrobes and pictures, in skirting boards, stored clothes and rarely used bedding, and it bites only when pressed against skin. Cutaneous loxoscelism begins as a pale, painful patch that darkens over a day or two into a slowly ulcerating wound; the rarer viscerocutaneous form, which mostly affects children, causes fever and haemolysis and is a medical emergency. Specific antivenom works best given early, so speed matters more than anything you can do at home.

Wandering spiders. Phoneutria nigriventer reaches the humid north-east — Misiones, Corrientes, Chaco and Formosa. It builds no web, hunts at night and shelters by day in banana bunches, woodpiles, boots and rubble. Most bites are dry or mild, causing immediate severe local pain and sweating; severe envenoming is uncommon and mainly affects small children. Treatment is pain control, observation and, in serious cases, arachnid antivenom.

What the older Argentina list gets wrong

The widow here is not Latrodectus curacaviensis. That species belongs to the Caribbean and northern South America. Argentina's widows of medical importance are L. mirabilis and L. corallinus, both spiders of open grassland rather than houses.

The golden silk orb weaver is Trichonephila clavipes. The genus was split from Nephila, so older pages carry the outdated name. The spider itself is unchanged: large, harmless and famous for its golden silk.

The pantropical huntsman is not dangerous. Heteropoda venatoria is fast, flat and alarming on a bedroom wall, but its bite is a brief local sting. Nor are Grammostola tarantulas dangerous; they flick irritating abdominal hairs long before they consider biting.

Where you meet them

In the house

The common house spider and small cobweb species take ceiling corners; the southern house spider fills cracks in exterior walls with pale lacy sheets. The one to know is the Chilean recluse, which prefers undisturbed storage: behind furniture, in boxes, inside clothes left folded for months. Our guide to house spiders covers indoor species in detail.

Gardens and the Pampas

Orb weavers work hedges, fences and tall grass. Widows live at ground level in rough grass, rubble, vacant lots and old farm equipment, which is where gloves are worth wearing.

The subtropical north

Misiones and the Chaco add golden silk orb weavers, green Lyssomanes jumpers and the wandering spiders. Shake out boots and check firewood and banana bunches here, not in Buenos Aires.

Spider season in Argentina

Seasons run opposite to the northern hemisphere. Spiders hatched in spring mature from late November, and activity peaks in the southern summer, December to March, when orb webs appear overnight in gardens and mature males wander in search of females. That wandering, not an invasion, is what puts hunting spiders indoors in midsummer. The nightly rebuilding behind those webs is covered in our guide to the spider web.

Recluse bites follow the same calendar for a different reason: summer clothing comes out of storage, so a spider that has sat undisturbed for months ends up against skin. In Patagonia the active season is much shorter, and most species overwinter as eggs or juveniles.

Easy mix-ups in Argentina

The southern house spider causes more false recluse reports than anything else. The female is dark and velvety and the male a leggy tan spider of roughly the right size, but both build a lacy crevice web, which a recluse never does, and both have eight eyes. A recluse has six eyes in three pairs and leaves only a scruffy retreat.

The false black widow, Steatoda grossa, is the usual stand-in for a true widow: purplish-brown with pale markings, common in sheds, and no threat. Harvestmen, with one fused body section and no venom glands, are not spiders, and the sun spiders of the Monte desert and Patagonia — fast, pale solifuges with oversized jaws — have no venom at all.

Common Spiders in Argentina

• Common House Spider (Parasteatoda tepidariorum)
• Adanson’s House Jumper (Hasarius adansoni)
• Pantropical Huntsman Spider (Heteropoda venatoria)
• Silver Garden Spider (Argiope argentata)

Biggest Spiders in Argentina

• Golden Silk Orb Weaver Spider (Trichonephila clavipes)
• Guarani giant tarantula (Grammostola grossa)

Most Venomous Spiders in Argentina

Cobweb Spiders/Tangle Web Spiders (Theridiidae)

Cobweb SpidersBrown Widow (Latrodectus geometricus)Identify the brown widow (Latrodectus geometricus) by its orange hourglass and spiky egg sac, and learn how its bite compares with a black wCobweb SpidersFalse Black Widow (Steatoda grossa)Identify the false black widow (Steatoda grossa): size, colour, its gumfoot cobweb, how it differs from a true widow, and how bad the bite r

Wandering Spiders

Wandering SpidersBrazilian Wandering (Phoneutria)Brazilian wandering spiders (Phoneutria): how to identify them, where the nine species live, what the venom really does, and what to do afte

Sicariidae Spiders

Sicariidae SpidersChilean Recluse (Loxosceles laeta)Identify the Chilean recluse (Loxosceles laeta): size, six eyes, faint violin, where it lives, and why its bite causes more systemic loxosce

Less Venomous Spiders in Argentina

Orb Weavers

Orb WeaversGolden Silk Orb-Weaver (Nephila)Golden silk orb-weavers (Nephila): huge females, tiny males, giant golden webs, where they live, what they eat and whether their bite is danOrb WeaversBanded Garden (Argiope trifasciata)Identify the banded garden spider (Argiope trifasciata): silver banding, size, the zigzag in its web, egg sac, range, and whether its bite iOrb WeaversSpinybacked Orbweaver (Gasteracantha cancriformis)Spinybacked orbweaver (Gasteracantha cancriformis) identification: six abdominal spines, colour forms, the silk-tufted web, range and whethe

Jumping Spiders

Jumping SpidersLyssomanesA guide to Lyssomanes, the translucent green jumping spiders of the Americas: how to identify them, where they live, what they hunt and whetJumping SpidersGray Wall Jumping (Menemerus bivittatus)Identify the gray wall jumping spider (Menemerus bivittatus): size, the flattened grey-haired body, its walls-and-tree-trunks habitat, and w

Cobweb Spiders/Tangle Web Spiders (Theridiidae)

Cobweb SpidersRed House (Nesticodes rufipes)Identify the red house spider (Nesticodes rufipes): rusty red body, tangled indoor web, why it is mistaken for a widow, and what its bite acCobweb SpidersTriangulate Cobweb (Steatoda triangulosa)Identify the triangulate cobweb spider (Steatoda triangulosa): the purple zigzag pattern, yellow legs, its tangle web, and whether the bite

Crevice Weaver Spiders (Filistatidae)

Crevice WeaversSouthern House (Kukulcania hibernalis)Identify the southern house spider (Kukulcania hibernalis): female and male size and color, the sunburst web, range, and why males are mista

Living with Argentina's spiders

Almost all risk comes from a spider being trapped against skin, so the useful habits are about storage rather than spraying:

• Shake out clothes, shoes and towels that have been folded or stored, especially at the start of summer.
• Keep beds away from walls, and do not let bedding or boxes touch the floor in rooms that are rarely used.
• Wear gloves for woodpiles, rubble, sheet metal and old machinery on farms.
• Vacuum webs, retreats and egg sacs rather than spraying, and fit door sweeps and screens.

For the neighbouring faunas, see Chile and Brazil.