Heterometrus silenus

Heterometrus silenus has a black exoskeleton with a greenish or bluish sheen, especially on the pincers. The pincers are broad and massive, and the tail (metasoma) is relatively short compared with the body. Like most scorpions it glows clearly under UV light.

Adults reach about 10–12 cm in length. Males and females look alike; males usually have slimmer pincers and longer pectines on the underside.

The species was described from Cochinchina, southern Vietnam. According to a 2023 revision it occurs in eastern Thailand as well as in Cambodia and Vietnam, and specimens have also been found west of Nakhon Pathom. Some Thai populations previously identified as H. laoticus were assigned to H. silenus.

The genus Heterometrus includes many similar species, and H. silenus, H. spinifer, H. laoticus and H. petersii are often confused in the trade. Ask about the origin of the line when buying.

A single adult scorpion needs an enclosure with a floor of about 40 × 30 cm. A deep substrate layer matters more than height: 10–15 cm of soil, coco fibre and peat, in which the scorpion digs a burrow. A flat piece of bark or a stone set firmly on the substrate gives it a starting point.

Heterometrus can climb silicone seams and rough walls, so the lid must be secure. Place heavy decor directly on the floor so the scorpion cannot be crushed while digging.

The species comes from humid forest and needs 24–28°C and substrate that stays slightly moist lower down. Water along the edge every few days so moisture soaks into the lower layers.

A shallow water dish is recommended. Humidity must not mean stale air: wet substrate without ventilation encourages mould and mites.

The scorpion hunts at night. Adults do fine with 2–3 large crickets or roaches every one to two weeks; feed juveniles smaller prey more often. Remove uneaten insects so they do not disturb the scorpion during a moult.

Scorpions give birth to live young, which ride on the mother’s back for the first weeks. Do not disturb the female during this time. Heterometrus live several years and usually mature after 2–3 years.

Heterometrus silenus is nervous: when disturbed it raises its pincers and tail and pinches if needed. A pinch from a large specimen is noticeable, and a sting is usually compared to a wasp sting, although allergic reactions are possible.

Use long tongs for maintenance and a container for rehousing. Do not handle the scorpion. Group keeping is practised, but it needs a large enclosure, many hides and generous feeding; keeping individuals singly is safer.