Grammostola grossa (Guarani Giant)

Grammostola grossa, commonly known as the Chaco Giant Tarantula, is a large, hardy, and long-lived terrestrial species native to the subtropical grasslands and dry forests of Paraguay, northern Argentina, and southeastern Brazil. Often mistaken for G. pulchripes in its juvenile stages, adults develop a darker, more subdued coloration—deep mahogany-brown to near black with dense reddish setae on the abdomen and legs that give a warm, earthy sheen. In the wild, G. grossa occupies self-dug or naturally occurring burrows in compact, clay-rich soils, emerging at dusk to hunt small invertebrates. This species endures both warm, humid summers and cooler, drier winters, making it remarkably adaptable and resilient in captivity. Calm, deliberate, and rarely defensive, it’s an excellent display or educational species known for its size, hardiness, and longevity. In captivity, it thrives in semi-arid setups with deep substrate, low-to-moderate humidity, and good ventilation—ideal for both beginners and seasoned collectors.

• Scientific Name: Grammostola grossa

• Common Name: Chaco Giant Tarantula

• Adult Leg Span: 7–8 inches

• Country of Origin: Paraguay, Argentina, Brazil

• Habitat: Subtropical Grassland and Dry Forest (200–800 m elevation); compact clay and loamy soils beneath vegetation and forest debris, ambient temperatures 74–84°F, relative humidity 60–70%, with distinct wet and dry seasonal cycles

• Habits: Terrestrial / Burrowing

• Growth Rate: Slow to Moderate