Javanimetrus cyaneus, commonly known as the Asian blue forest scorpion, is a large species of scorpion belonging to the family Scorpionidae. Formerly classified under the genus Heterometrus, it was reclassified following a revision of the genus. 
 
Physical Characteristics
Appearance: These scorpions are predominantly dark black but are distinguished by notable blue reflections or a blue-ish sheen on their exoskeleton.
Size: They are quite large, typically reaching lengths of 12 to 15 cm (approximately 4.7 to 5.9 inches). Some specimens recorded in trade have reached up to 18 cm.
Texture: The body is strongly granulated, giving it a rough texture. 
 
Distribution and Habitat
Native to Southeast Asia, J. cyaneus is primarily found in:
Indonesia (specifically Java and Borneo).
The Philippines.
Thailand.
Habitat: They inhabit tropical rainforests and wetland forests, where they typically hide under stones, fallen trees, or in shallow burrows. 
 
Behavior and Toxicity
Temperament: While sometimes kept as pets, they are generally more defensive than the popular Emperor scorpion (Pandinus imperator). They are quick to assume a defensive posture and prefer using their powerful pincers over their stinger.
Venom: Their sting is considered mild to moderately painful for humans, often compared to a bee sting. While painful, the venom is not considered medically significant for healthy adults.
Social Nature: They are known to be somewhat communal and can sometimes be kept in groups if provided with sufficient space and food, though individual aggression can still occur. 
 
Captive Care
For those keeping them in 2026, standard care requirements include:
Temperature: Ideally maintained between 22°C and 28°C.
Humidity: High humidity levels of 70% to 80% are necessary to mimic their rainforest habitat.
Diet: In captivity, they feed on insects such as crickets, mealworms, and roaches.