Amami Lesser Stag Beetle

Amami Lesser Stag Beetle key facts

Care level

Intermediate

Lifespan

6 months to 2 years as an adult

Size

Males 21.3-36.2mm, females 22-28mm

Diet

Adults take sap of broadleaf trees and beetle jelly; larvae feed on soft rotten wood

Temperature & Humidity

The larvae live in fairly damp, soft rotten wood, so neither the laying log nor the rearing medium should be allowed to dry out.

Breeding & Egg-laying

Females lay in rotten broadleaf wood along streams. The larvae hatch about a month after laying, feed on soft rotten wood and take about a year to develop. Final-instar larvae begin building a pupal chamber in the autumn of that year or the following spring, spend about a month becoming a pupa and eclose about a month after that.

Cohabitation

As with stag beetles generally, males fight, so keep adults singly. Beetles from anywhere other than Amami-Oshima and Kakeromajima belong to other subspecies and must not be housed or crossed with them.

Lifespan & Rearing Period

Adults live from six months to two years. Those that eclose in autumn overwinter and become active the following spring, while those that eclose in spring leave the pupal chamber after about a month.

Health & Notes

The 2025 edition of BE-KUWA lists a captive record of 40.8 mm (Kenichi Nakaya, 2009) and a wild record of 37.8 mm (Yusuke Takamochi). The beetle is not as numerous as the mainland lesser stag, so keep collecting to a minimum and do not release captive stock into the wild. Females are easily confused with those of Rhaetulus recticornis, so check the swellings on the head.

About Amami Lesser Stag Beetle

Meet the Amami Lesser Stag Beetle, a small subspecies found only on Amami-Oshima and Kakeromajima. Learn about its size, care basics, single-adult housing, and 6-month-to-2-year adult lifespan.

7 things to know before welcoming a Amami Lesser Stag Beetle

1. 1Found Only on Two Islands

   The Amami Lesser Stag Beetle is found only on Amami-Oshima and Kakeromajima, and wild populations are not abundant. It's worth checking the background of any individual you bring home, simply to understand where it came from.

2. 2Small Body, Bold Jaws

   Among Japan's lesser stag beetles, this is one of the smallest, yet its mandibles are short and strongly curved. Adults typically measure 21.3–36.2mm for males and 22–28mm for females, a size worth comparing against other lesser stag beetle species.

3. 3Built for Life in Trees

   Its legs and tarsi are relatively long, an adaptation well suited to climbing among trees. Adding branches or bark inside the enclosure lets it move and perch more naturally, making its behavior easier to observe.

4. 4Keep Adults Individually

   As with stag beetles in general, males fight one another, so adults should be kept individually. Individuals from localities other than Amami-Oshima and Kakeromajima belong to other subspecies, so never house or breed them together.

5. 5Best Suited to Intermediate Keepers

   This species is generally considered suitable for keepers with some prior insect-keeping experience rather than absolute beginners. Setting up an environment where you can easily notice small shifts in temperature and humidity will make day-to-day care much easier.

6. 6Adults Live 6 Months to 2 Years

   Adult lifespan ranges widely, from about six months to two years. Knowing roughly when an individual emerged as an adult can help you get a sense of how much time you may spend together.

7. 7Prepare the Enclosure First

   Before bringing one home, set up the basics — insect mat substrate, climbing branches, and a well-ventilated case. Arranging the enclosure with its tree-dwelling habits in mind helps a new beetle settle in more quickly.

Frequently asked questions about Amami Lesser Stag Beetle

Q.Is the Amami Lesser Stag Beetle suitable for beginners?

A.This species is generally considered better suited to keepers with some prior insect-keeping experience rather than complete beginners. Learn the basics first, including temperature and humidity management, and care for it attentively.

Q.How large do they grow?

A.Adults typically measure 21.3–36.2mm for males and 22–28mm for females. That makes them one of the smaller members of Japan's lesser stag beetle group.

Q.How long do adults live?

A.Adult lifespan ranges from roughly six months to two years, varying by individual. Differences in care and condition can affect how long a beetle lives.

Q.Can I keep several together?

A.As with stag beetles in general, males fight one another, so adults should be kept individually. Individuals from localities other than Amami-Oshima and Kakeromajima are different subspecies, so do not house or breed them together.

Q.What kind of enclosure setup do they need?

A.Because their body is adapted for climbing, adding branches or bark gives them natural perches to display their tree-dwelling behavior. A well-ventilated case with insect mat substrate, plus attention to temperature and humidity, rounds out the basic setup.

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