
Source: Wikimedia Commons
Eupatorus siamensis
A five-horned beetle centred on north-eastern Thailand. It carries one horn on the head and four on the prothorax, short horns set on a black body. The BE-KUWA captive record, registered in 2025, stands at 81.6 mm.
Eupatorus siamensis was described by Castelnau in 1867, and the English Wikipedia gives its range as the Isan region of north-eastern Thailand and Cambodia. GBIF holds most records from Thailand, followed by Vietnam and Cambodia. As in the rest of the genus it carries five horns, one on the head and four on the prothorax. The Japanese Wikipedia notes that the genus lives on the Southeast Asian mainland, inhabits bamboo groves and drinks the sap of new shoots, while also visiting tree sap and fruit. The BE-KUWA FY2025 edition lists a captive record of 81.6 mm set by 菅 勇人 in 2025, with a projected maximum of 87 mm. Among the four species of the genus that carry a BE-KUWA record, its figure is second only to that of Eupatorus gracilicornis, and live stock is bred in Japan.
Source: Wikipedia (CC BY-SA 4.0)
The Siamese Five-horned Beetle lives Adults 3-6 months.
The Siamese Five-horned Beetle grows to Captive record for males 81.6 mm (BE-KUWA FY2025 edition; projected maximum 87 mm).
Origin
Indochina (mainly the Isan region of north-eastern Thailand, plus Cambodia and Vietnam)
Lifespan
Adults 3-6 months
Size
Captive record for males 81.6 mm (BE-KUWA FY2025 edition; projected maximum 87 mm)
Sources: Eupatorus siamensis - Wikipedia (EN; range in Isan, Thailand and Cambodia) / Eupatorus - Wikipedia (JA; member species, Japanese names, bamboo-grove habits, horn arrangement) / GBIF species page for Eupatorus siamensis (distribution and occurrence records by country) / BE-KUWA Certified Breeding Records (Mushi-sha, FY2025 edition PDF, JA) / Ben's Beetle Breeding Pages - Eupatorus hardwickei (range; the inactive-F1 problem; larval period)
Captive record (♂)
81.6 mm
Record source: BE-KUWA 2025 edition (Siamese five-horned beetle, captive 81.6 mm, 菅 勇人 2025; projected maximum 87 mm)
Notable localities
The captive record was updated in 2025 and the projected maximum is 87 mm. The rhinoceros-beetle table carries no wild-record column, so no wild figure is given.
Generation codes
Sources: BE-KUWA Certified Breeding Records (Mushi-sha, FY2025 edition PDF, JA)
Edited & verified by: BreederDirect editorial team
The taxonomic, regulatory, and husbandry data on this page are compiled and verified against the authoritative primary sources below.
Primary sources
Accepted name: Eupatorus siamensis (Castelnau, 1867)
Authority databases: GBIF
Nomenclature follows global taxonomic authority databases.
Plant Protection Act: When importing live specimens of Scarabaeoidea (including rhinoceros beetles, stag beetles, flower beetles, etc.), a species identification certificate issued by the exporting country government agency or equivalent must be attached in accordance with the Invasive Species Act (import ports are limited to Narita, Chubu, Kansai, Fukuoka, and Kagoshima airports). This species itself is not a designated invasive species, and import is possible upon submission of the certificate.
Sources: Ministry of the Environment, Invasive Species Act: "Guidance for Those Importing Live Insects in Scarabaeoidea" / CITES Appendix (checklist.cites.org)
Regulations may change. Always verify the latest information with the relevant authorities.
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Temperature
20〜28℃
Humidity
60〜80%
Sap of bamboo shoots, tree sap and fruit; beetle jelly
No published figures for rearing temperature or humidity exist for this species, so none are given. It comes from bamboo groves in Indochina, so keep it at room temperature away from heat and hold the substrate short of drying out.
The 2025 BE-KUWA captive record shows that the species does breed in captivity. Attempt egg-laying in a deep set of fermented substrate. In this genus freshly emerged adults are known to stay inactive for a long time; beetlebreeding.ch reports an inactive period of up to a year in a congener.
Keep adults singly. Males shove each other with their horns, so do not house them together. Pair them only for the short time needed to see mating.
Dormancy after emergence is long and activity may not begin for several months. Any estimate of the time needed must allow for that on top of the larval period, for which no measured figure has been published for this species.
Importing live beetles requires the species identification certificate demanded for live Scarabaeoidea. Horn tips chip easily once dry, so handle the beetle as little as possible.
Intermediate. This is an intermediate-level species. Some prior experience and knowledge of environmental management are recommended.
The average lifespan of Siamese Five-horned Beetle is Adults 3-6 months. With proper care and nutrition, they can live a long and healthy life.
Siamese Five-horned Beetle typically reaches Captive record for males 81.6 mm (BE-KUWA FY2025 edition; projected maximum 87 mm) as an adult. Size may vary depending on care conditions and individual genetics.
Siamese Five-horned Beetle feeds on: Sap of bamboo shoots, tree sap and fruit; beetle jelly. Aim for a balanced diet with appropriate feeding frequency.
The price of Siamese Five-horned Beetle varies significantly depending on bloodline, size, captive-bred generation, and sex. Check our market price page for the latest pricing information.
Last updated: September 17, 2026