Asian Forest Scorpion

Asian Forest Scorpion（圖片來源：Michiel de Groot，採用 CC BY 4.0 授權）

The Asian forest scorpion (Heterometrus longimanus) is a large scorpion distributed across tropical Southeast Asia. It mainly inhabits humid rainforests in Indonesia, Malaysia, the Philippines, and Borneo. Adults typically reach a body length of 10 to 12 centimeters. Their bodies are glossy black, while the sting at the tip of the tail is usually dark brown or reddish brown. This species has a striking and intimidating appearance. In males, the pedipalps are more elongated than in females, and the tail is also slightly longer. This sexual dimorphism becomes visible only after the scorpions reach adulthood, which makes juveniles and subadults difficult to sex.

In the wild, the Asian forest scorpion commonly lives beneath rotting wood, leaf litter, and moist soil on the forest floor. It may dig burrows beneath tree roots, and when ground conditions become too wet it may temporarily climb tree trunks or shelter in tree cavities. Because of this flexibility, the species shows both burrowing behavior and occasional semi-arboreal activity. It is also highly adaptable to environmental disturbance. Even in urban green spaces or modified habitats, individuals can survive by sheltering beneath exposed roots or fallen wood along roadsides.

Ecologically, the Asian forest scorpion is a nocturnal predator. During the daytime it usually hides inside burrows or other sheltered places, emerging at night to hunt. Its eyesight is poor, but the body is covered with fine sensory hairs and specialized sensory organs. Among these are the comb-like pectines located on the underside of the body, which detect ground vibrations and help locate prey. The scorpion mainly feeds on arthropods such as crickets, cockroaches, and spiders, although it may occasionally capture small lizards or frogs. Despite its fierce appearance, the species is generally calm and rarely attacks unless disturbed. Its venom is relatively mild, and stings typically cause only brief burning pain and minor swelling in humans, making it a species of little medical concern.

The Asian forest scorpion is viviparous. The gestation period may last from ten months to one year. After birth, the young climb onto their mother's back and remain there until they complete their first molt. The mother assists by tearing prey into smaller pieces so the young can feed. This behavior represents a relatively advanced form of maternal care among arthropods. Juveniles typically molt six to seven times before reaching adulthood. The entire growth process takes about one year, and individuals may live as long as ten years.

Asian Forest Scorpion（圖片來源：Philipp Hoenle，CC0 1.0 公共領域）

Housing Requirements in Captivity

Under captive conditions, the Asian forest scorpion is fairly tolerant of husbandry conditions, but replicating aspects of a tropical forest environment will help maintain long-term health. Because this species is a ground-dwelling burrowing scorpion, the enclosure should prioritize floor space rather than height. A single adult can be kept in a glass or acrylic terrarium measuring approximately 55 centimeters in length, 30 centimeters in width, and at least 30 centimeters in height.

The substrate layer should be at least 5 centimeters deep. A moisture-retentive substrate mixture is recommended, such as coconut fiber, peat soil, and decomposed leaf litter in a ratio of about 5:1, with sphagnum moss added to maintain humidity.

Temperature should be maintained between 24 and 30°C, and nighttime temperatures should not fall below 22°C. Since scorpions cannot regulate their own body temperature, the most suitable heating method is a heating pad attached to the outside wall of the enclosure. The heating pad should not be placed beneath the tank, because scorpions tend to burrow toward heat sources and may overheat.

Humidity should remain between 70% and 80%. This can be achieved by occasionally misting the substrate or placing damp sphagnum moss in a corner of the enclosure. However, standing water should be avoided because it encourages mold and mites. Water should never be sprayed directly onto the scorpion, as they are highly sensitive to sudden droplets.

Several hiding places should be provided inside the enclosure, such as pieces of bark, hollow logs, coconut shells, or flat stones. Each scorpion should have access to its own shelter, which reduces stress and decreases the likelihood of aggressive encounters. Special lighting equipment is unnecessary. These scorpions avoid strong light and only require a normal day–night cycle. If observation is desired, a red light or ultraviolet lamp can be used briefly, but prolonged exposure should be avoided to prevent stress.

A water dish should always be present. It should be shallow and wide so the scorpion can easily climb out. If the water level is relatively deep, small stones may be added to prevent drowning. Dechlorinated water or bottled mineral water is recommended.

Housing adult individuals together is generally not recommended. Although juveniles live communally while on their mother's back, they gradually develop territorial behavior as they grow. Some keepers have successfully maintained small groups, but this requires a spacious enclosure, abundant hiding places, and plentiful food, along with close monitoring for aggression. In most situations, solitary housing remains the safest approach, especially because adult females may become strongly defensive.

Feeding Conditions

The Asian forest scorpion is a carnivorous predator that feeds primarily on live prey. In the wild it hunts insects and other small invertebrates, and occasionally captures small frogs or lizards of similar size. In captivity, suitable prey items include crickets, cherry roaches, Dubia roaches, and mealworms.

Adult scorpions can be fed once per week, usually receiving two to three large crickets per feeding. If environmental temperatures are lower or activity levels decrease, they may naturally reduce their feeding frequency.

Scorpions typically ambush prey rather than actively chasing it. Therefore, feeder insects should be active but not prone to escaping or burrowing into the substrate. If flying or jumping insects are used, their wings or legs can be trimmed beforehand. Juvenile scorpions should be provided with smaller insects or pre-killed prey to prevent injury. Any uneaten food remaining the following day should be removed immediately to prevent decay and fungal growth.

Keepers sometimes observe that scorpions refuse food when preparing to molt or after being moved to a new enclosure. During such periods feeding attempts should be minimized, while maintaining stable environmental conditions. Adult scorpions are capable of surviving long periods without food, sometimes several months, which is a normal physiological condition. On the other hand, if the abdomen becomes excessively swollen and the gaps between exoskeleton segments widen, the scorpion may be overfed, and feeding intervals should be increased.

Dusting feeder insects with calcium or vitamin powder is unnecessary because scorpions mainly consume the internal fluids of their prey rather than the exoskeleton. If additional nutrition is desired, feeder insects can be gut-loaded by feeding them fruits, vegetables, or oats the day before they are offered to the scorpion.

Breeding Conditions

Asian forest scorpions reach sexual maturity at approximately two to three years of age. During courtship the pair performs the characteristic “scorpion dance.” The male grasps the female with his pedipalps and leads her back and forth across the ground while searching for a suitable place to deposit a spermatophore. When the female's genital opening comes into contact with the spermatophore, fertilization occurs. After mating, the pair should be separated immediately, because the female may become defensive and attack the male.

The gestation period lasts about nine to twelve months, and each brood typically contains between 20 and 40 offspring. Newly born scorpions are soft and milky white and cling tightly to the mother's back for several days. They begin independent movement only after completing their first molt. During this stage separate feeding is unnecessary as long as the mother has enough food. She will tear apart prey so that the juveniles can feed.

Maintaining temperatures between 26 and 30°C and humidity above 80% can improve juvenile survival rates. Once the young leave the mother's back, they can be moved into small ventilated containers lined with moist coconut fiber substrate and provided with hiding places. Juveniles can be fed small crickets, fruit flies, or very small mealworms twice per week.

If sufficient food is available, juveniles may remain with the mother for some time. Some studies suggest that species of the genus Heterometrus may form temporary subsocial groups in which mothers and offspring share burrows and remain in proximity while hunting. As the young continue to grow, however, they generally disperse.

Under captive conditions, breeding this species is relatively straightforward as long as warm and humid conditions are maintained. Because females may produce multiple broods after a single mating, keepers should prepare adequate space for the offspring in advance to prevent overcrowding and aggressive interactions.

Preventing Invasive Spread

The Asian forest scorpion originates from tropical Southeast Asia. In recent years, rainforest scorpions from Asia have become popular in the global pet trade because of their impressive appearance. If individuals are released, abandoned, or escape in regions outside their native range, they may cause ecological disturbances, including impacts on local insect communities.

For this reason, keepers must strictly follow the principle of never releasing or abandoning captive animals. If continued care is no longer possible, the scorpion should be transferred to a responsible keeper or surrendered to a legitimate animal rescue organization rather than released into the wild. When acquiring this species, it is also recommended to choose captive-bred individuals rather than wild-caught specimens from Southeast Asia, which helps reduce illegal collection and wildlife trafficking.

Author: Shui-Ye You