Hachijo Flat Stag Beetle
The Hachijo Flat Stag Beetle is a stag beetle subspecies found only on Hachijojima, one of the Izu Islands. It closely resembles the mainland Japanese flat stag beetle, though some males can be distinguished by a first inner tooth positioned closer to the tip of the mandible. Due to habitat decline, it was listed as Vulnerable on the Ministry of the Environment's 2020 Red List, making it a scarce regional population that draws attention from enthusiasts. Adults live one to three years, a fairly long lifespan for a stag beetle, offering keepers time to grow attached. Males reach 45–73mm and females 22–33mm, and since care is considered intermediate-level, it suits keepers who already have some basic stag beetle experience.
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Hachijo Flat Stag Beetle key facts
- Care level
- Intermediate
- Lifespan
- Adults 1-3 years
- Size
- Males 45-73 mm (including captive; wild up to 60.3 mm) / females 22-33 mm
- Temperature
- 20〜26℃
- Diet
- Tree sap, beetle jelly
- Temperature & Humidity
- Keep at about 20-26 C. From mild Hachijojima but a temperate beetle close to the mainland lineage; larvae do not survive below 0 C, so never let them freeze. Keep the substrate moist enough to clump when squeezed.
- Breeding & Egg-laying
- Females lay in the buried base of dead standing hardwood or under fallen logs. In captivity bury fairly soft logs in fermented substrate and rear larvae in substrate or fungus bottles. Larvae take 1-2 years.
- Cohabitation
- Aggressive; males can kill females. Keep singly and pair only for a few days under supervision.
- Lifespan & Rearing Period
- Adults live 1-3 years and overwinter. Newly emerged adults stay in the pupal cell about a month before becoming active.
- Health & Notes
- Listed as Vulnerable on the Ministry of the Environment Red List 2020. Avoid wild collecting, keep captive-bred stock, and never release beetles. The grip is strong, so handle with care.
About Hachijo Flat Stag Beetle
A rare stag beetle subspecies found only on Hachijojima, Japan, listed as Vulnerable. Adults live 1–3 years, with males reaching 45–73mm and females 22–33mm; care is intermediate-level.
7 things to know before welcoming a Hachijo Flat Stag Beetle
1A Rare Island Subspecies
This subspecies is found only on Hachijojima in the Izu Islands and was listed as Vulnerable on the Ministry of the Environment's 2020 Red List. Given its rarity, keepers should handle it with extra care.
2How Males Are Identified
Males closely resemble the mainland Japanese flat stag beetle, though some individuals have a first inner tooth positioned closer to the tip of the mandible. This trait varies between individuals and isn't seen in every male.
3A Long Adult Lifespan
Adults typically live one to three years, which is relatively long for a stag beetle. With stable temperatures and consistent feeding, keepers can enjoy watching them for an extended period.
4Size Varies by Individual
Males typically reach 45–73mm and females 22–33mm. Wild males have been recorded up to 60.3mm, though captive-bred individuals can sometimes grow larger.
5Intermediate-Level Care
This species calls for solid basic knowledge of stag beetle keeping, including temperature and humidity control. First-time keepers may want to start with an easier species before taking one on.
6Never House Males Together
Male stag beetles are territorial, and housing multiple males together risks injury from fighting with their mandibles. Keep one male per enclosure as a rule.
7Prepare the Habitat First
Before bringing one home, set up insect substrate, wood pieces to prevent the beetle from getting stuck on its back, and a spot with stable temperature. During its active season, mist occasionally to maintain adequate humidity.
Frequently asked questions about Hachijo Flat Stag Beetle
- Q.Is this beetle suitable for beginners?
- A.It's considered an intermediate-level species, so it's best to have some experience with basic stag beetle care, such as temperature and humidity control, before taking one on. First-time keepers may want to start with an easier species.
- Q.How large does it grow?
- A.Males typically reach 45–73mm and females 22–33mm. The largest recorded wild male is 60.3mm, though captive-bred individuals have been reported to grow even larger.
- Q.How long do adults live?
- A.Adults generally live for one to three years. With proper temperature control and consistent feeding, keepers can enjoy a long observation period.
- Q.How is it different from the mainland flat stag beetle?
- A.It looks very similar to the mainland Japanese flat stag beetle, but it's a subspecies found only on Hachijojima in the Izu Islands. Some males can be distinguished by a first inner tooth positioned closer to the tip of the mandible.
- Q.Is the Hachijo Flat Stag Beetle listed under CITES?
- A.No, it is not subject to CITES.
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