Geodorcus helmsi

If you’re ever out at night in the forests of the western South Island, keep an eye out for Geodorcus helmsii, the Helm’s stag beetle, hanging out on the trunks of trees.

Widespread throughout Te Wai Pounamu, Rakiura, and other southern islands, these native beetles are large, slow-moving, and flightless. They come out at night to feed on sap seeping out of tree trunks. During the day, they chill under logs, stones, or fallen leaf litter on the forest floor. You can find them in forests and tussock lands from sea level to 1400m!

All Helm’s stag beetles are black or brownish-black, and the males are bigger than the females. Males can be up to 44mm long with shiny black heads decked out with a powerful pair of mandibles – the stag-horn-looking pincers from which stag beetles take their name.

Despite being one of Aotearoa’s most iconic beetle species, we still don’t know a lot about its lifecycle and behaviour. Stag beetles like this one are facing several threats and are easy meals for rats and pigs. Helm’s stag beetles are one of the only insects protected under the Wildlife Act (1953), which means it’s illegal to collect, kill, or possess a specimen.

Check these links for more info on the Helm’s Stag Beetle in NZ Observations of Geodorcus helmsi

Wikipedia: Information on Geodorcus helmsi

Radio New Zealand (Our Changing World): The Battling Beetle (2022)

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Click on the image to visit the official observation. image © Thor Elley image © Jean Roger