Biosecurity New Zealand has confirmed that the varroa honey bee mite has been found in hives in North Canterbury, well outside the current South Island control area.
Last month the agency confirmed a revised containment zone designed to slow the pest's spread from the Nelson and Marlborough regions, where it is now established.
Biosecurity NZ incursion manager Richard Norman says a suspected varroa infestation in the Rangiora area, reported by a hobbyist beekeeper, has been confirmed by laboratory tests.
Mr Norman says more suspected infestations have since been reported.
He says funding set aside to control the spread of the varroa mite includes a condition that the control line is not breached, so a decision will have to be made whether to continue that work.