Geodorcus ithaginis
A sea stack in the Mokohinau Islands known only as ‘Stack H’ may or may not be the last remaining home for our rarest beetle. Their habitat is the size of a generous living room; they have been predated out of existence everywhere else. They are so extraordinarily rare that their home can’t be revealed as unscrupulous poachers and collecters of endangered and precious creatures could feel compelled to liberate these beetles from their remote sea stack.
They are a good-sized beetle, the males up to 32mm long, the females slightly smaller, pleasingly stocky, flightless, and a slow perambulator, which is fortunate, because there is nowhere much for them to go on Stack H. The males have a protruding mandible used for battling other males for beetle supremacy.
Silver brooch
Stag beetles are under threat worldwide, mainly because of habitat loss. It takes a long time to become a stag beetle; they live as larvae underground for years before briefly becoming a beetle, and require a stable habitat of rotting logs and leaf litter in order to ensure their survival. The Mokohinau stag beetles do not have the luxury of leaf litter on their stack. They live amongst the peat-like substance that forms beneath the New Zealand ice plant, in tussock plants, and under rocks. Only rugged, sea-battered pohutukawa provide fallen leaves for beetles on Stack H.
Silver brooch
At the start I mentioned that Stack H may not be the last remaining home for the Mokohinau stag beetle… this is not because they may have another as yet undiscovered home. Unfortunately a recent attempt at a stocktake of the beetle numbers was an abject failure. Not a single beetle was located, despite repeated fruitless searches. Quite simply, there was no evidence of the beetle to be found. There is a slim possibility that there are some as yet unmetamorphosed larvae underground, and something has befallen the adult population, but more likely they have disappeared forever, another victim of habitat loss and predation by introduced species.
Silver brooch