
Source: Wikimedia Commons
Phalacrognathus muelleri
The world's most beautiful stag beetle from Australia. Iridescent metallic rainbow body is its defining trait. Docile and easy to keep. Larvae thrive on both fungus bottles and substrate.
Phalacrognathus muelleri, the rainbow stag beetle, is the sole species in its genus and belongs to the family Lucanidae. Native to the rainforests of northern Queensland, Australia, and New Guinea, it is celebrated for its remarkable iridescent coloration, appearing in red, green, blue, or black forms depending on the individual. Adults reach 30–65 mm in length and inhabit tropical forest canopies, feeding on tree sap and fruit. In captivity, small to medium enclosures are suitable, furnished with pieces of bark and wood to prevent toppling. Egg-laying occurs directly in fine-particle fermented substrate packed to a depth of at least 10 cm. Its spectacular coloration, manageable size, and straightforward husbandry make it one of the most sought-after display beetles worldwide.
Source: Wikipedia (CC BY-SA 4.0)
The Rainbow Stag Beetle lives Adult 1-2 years / Larva ~8 months.
Optimal temperature is 20–25°C, and adults live one to two years—an unusually long lifespan for stag beetles.
The Rainbow Stag Beetle grows to 30-70mm.
The ideal temperature for the Rainbow Stag Beetle is 20〜26℃.
Origin
northern Queensland, Australia and New Guinea
Captive record (♂)
70.1 mm
Wild record (♂)
70 mm
Record source: BE-KUWA 2025 edition (Rainbow-colored - captive 70.1 mm Iijima Kazuhiko 2023 / wild 70.0 mm)
Notable localities
Characterized by metallic iridescent coloration. Easy to keep and popular. Captive breeding records are updated annually through BE-KUWA (Mushi-sha) competitions. Individual value varies significantly depending on locality, generation (CBF/WF/WD), and size.
Generation codes
Sources: BE-KUWA Certified Breeding Records (Mushi-sha, FY2025 edition, 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.
Accepted name: Phalacrognathus muelleri (MacLeay, 1885)
Synonyms: Lamprima muelleri MacLeay, 1885, Phalacrognathus muelleri fuscomicans Kolbe, 1908, Phalacrognathus westwoodi Shipp, 1893
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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Lifespan
Adult 1-2 years / Larva ~8 months
Size
30-70mm
Temperature
20〜26℃
Humidity
60〜80%
Jelly (adult) / Fungus bottle or fermented substrate (larva)
Small-medium case. Add plenty of bark to prevent flipping
Lays in substrate. Pack fine fermented mat deeply
Both fungus bottles and substrate work. Temperature is key to size
Adults take 2-3 months before starting to feed after eclosion
Beginner. This is a beginner-friendly species. No special equipment or experience is required, and it can be kept successfully with basic care setup.
The ideal temperature for Rainbow Stag Beetle is 20〜26℃. Avoid sudden temperature changes and maintain a stable environment.
The average lifespan of Rainbow Stag Beetle is Adult 1-2 years / Larva ~8 months. With proper care and nutrition, they can live a long and healthy life.
Rainbow Stag Beetle typically reaches 30-70mm as an adult. Size may vary depending on care conditions and individual genetics.
Rainbow Stag Beetle feeds on: Jelly (adult) / Fungus bottle or fermented substrate (larva). Aim for a balanced diet with appropriate feeding frequency.
The price of Rainbow Stag Beetle varies significantly depending on bloodline, size, captive-bred generation, and sex. Check our market price page for the latest pricing information.
Last updated: August 31, 2026