A remarkable discovery in the Ashburton Lakes has brought new hope - and real excitement - for the critically endangered Canterbury knobbled weevil beetle.

John Evans spotted three of the rare weevils on a speargrass plant while clearing traps, sharing photos on citizen science network iNaturalist and a bug identification group.

The images quickly drew attention from experts, prompting the Department of Conservation (DOC) to investigate.

DOC technical advisor Warren Chinn conducted a site survey, uncovering 41 weevils and confirming the species' identity.

Previously, the only known population was at Burkes Pass, near Tekapo, where numbers had dwindled to critically low levels.

This new population, located about 80km away, offers a significant boost for the species, once thought extinct until rediscovered in 2004.

Evans, a farmer with a keen eye for insects, was astonished by the find, describing the weevils as unusually large.

“It was so big!” John said.

DOC senior science advisor Tara Murray called the discovery a “game changer” but cautioned that both populations remained vulnerable to threats like fire and poor growing conditions for speargrass, the weevils’ sole habitat.

The species remains strictly protected under the Wildlife Act.