Chinese Stag Beetle
Dorcus hopei
A wrestler competing for a sip of sap
Male Chinese Stag Beetles carry a pair of stout jaws (mandibles) on the head, used as weapons in fights over sap and mates. Mandible length is strongly shaped by nutrition during the larval stage, so brothers from the same brood can emerge with wildly different jaw sizes — and very different fortunes as a result.
Key figures
- Length
- Males about 30–75 mm including the mandibles; females are smaller with underdeveloped mandibles
- Life cycle
- Larvae develop in rotten wood for 1–3 years; adults can live several months or more
- Habitat
- Rotten wood and tree hollows in broadleaf forest; often found at night on sap-oozing tree trunks
- Diet
- Larvae feed on decaying wood fiber; adults lick sap oozing from tree trunks
- Combat
- Males grip and flip rivals with their mandibles to win a feeding spot on the sap flow and access to mates
- Mandible Form
- Mandible length is shaped by larval nutrition, leading to wide variation between individuals
Life cycle
Egg → Larva (1–3 years) → Pupa → Adult
Ecological role
Chinese Stag Beetle larvae feed on and break down wood fiber in rotten logs, playing a part in the forest’s deadwood decomposition cycle; adults gather at sap wounds on tree trunks, sharing the limited feeding sites with other stag beetles and rhinoceros beetles.
Did you know
When brood-mates get very different nutrition as larvae, the resulting males can emerge with mandibles differing in length by more than twofold — small-jawed males often turn to sneak tactics instead of combat.
Range
Most of China, the Korean Peninsula, and Japan
Status
Common; some large individuals are captive-bred for the pet trade
Anatomy
- Mandibles — Toothed on the inner edge; used in combat to grip and flip a rival over
- Elytra — Glossy black and hard, covering the folded membranous hindwings underneath
- Head — Broad and flat, with well-developed muscles on either side that give the mandibles their powerful bite
- Antennae — The comb-like (lamellate) tips can open and close, used to detect the scent of sap
- Legs — Tarsi tipped with sharp claws that hold firm against the tension of a fight while gripping bark
- Pronotum — Slightly raised at the edges, forming a defensive shield together with the head
Open the interactive 3D specimen