Chalcosoma atlas

Primarily nocturnal and crepuscular, adults are strong fliers that visit tree sap flows, fermenting fruit and wounds for carbohydrate-rich food. Males use their horns to lift, pry and flip rivals during contests for feeding sites and mating access; otherwise adults are relatively slow-moving and solitary.

Females lay eggs in rich, decaying wood or humus; larvae are C-shaped grubs that feed on rotting timber and organic matter. Larval development is long (often 12–18+ months, depending on temperature and food), followed by pupation in a soil or wood cell and a short-lived adult stage focused on reproduction.

Marked sexual dimorphism: males possess prominent cephalic and thoracic horns and reach much larger sizes (some specimens >60–100 mm), while females are smaller and hornless. The exoskeleton is usually black to dark brown with a metallic sheen; legs are stout with digging adaptations and adults have powerful mandibles for handling food and gripping during fights.

Described from Southeast Asia, Chalcosoma atlas has long been prized by entomologists and collectors for its size and dramatic horn morphology. It features in local insect-keeping and hobbyist beetle-fighting traditions (where practiced), and has been prominent in natural-history collections since the 19th century.

There is no widespread global threatened-species listing for the Atlas beetle as a whole, but many local populations are vulnerable to habitat loss (deforestation, plantation expansion) and overcollection for the pet and specimen trade. Conservation depends on preserving mature tropical forest, retaining deadwood resources for larvae, and encouraging sustainable collecting practices.