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Prosopocoilus savagei (Hope, 1842)

A stag beetle in which the male weapon can grow out of proportion to the rest of the body, creating radically different adults from the same species.

About this species

Prosopocoilus savagei(Hope, 1842)

Information reviewed15 July 2026

Prosopocoilus savagei is a Central and East African stag beetle noted for extreme male variation. Females remain compact, while well-fed males can develop bodies and antler-like mandibles more than twice the female length.

Taxonomy

Animalia · Arthropoda · Insecta · Coleoptera · Lucanidae · Prosopocoilus

Accepted taxon. · checked 2026-07-15

Central and East AfricaBroad range and selected reference localities — not a complete occurrence map.

Size

Males about 24–65 mm; females about 21–31 mm.

Distribution

Central and East Africa

Habitat

Tropical forest and woodland containing decaying buried logs.

Activity

Adults are mainly crepuscular or nocturnal and visit sap or overripe fruit.

Diet

Tree sap and fermenting fruit as adults; decomposing wood as larvae.

Social structure

Solitary; males contest access to females and feeding sites.

What makes this species remarkable?

This species became a textbook illustration of static allometry: as a male grows larger, its mandibles increase disproportionately, so a large male is not merely a scaled-up small one but a differently armed animal.

The largest documented males reach about 65 millimetres while females remain near 31 millimetres, meaning sexual selection can more than double the apparent length of one sex without enlarging the other.

A female places eggs in medium-decayed wood, and the grub spends roughly a year converting a buried log into body tissue before sealing itself into a pupal chamber and rebuilding into an adult.

Sources and scientific references