The forest ringlet and its precarious balance has sparked the interest of Steve Wheatley, from Sir David Attenborough's Butterfly Conservation.
Mr Wheatley will come to Northland in the summer, when the forest ringlet is known to breed, to carry out critical field research.
He will work with New Zealand entomologists in researching causes of decline, the variables in different populations, and larval food plants to determine a preference for particular hosts or predator insects such as wasps.
Ms Knight said people seldom see the forest ringlet as it lives high in the canopy.
About the size of a cabbage white butterfly, it was once common throughout the country but is now found in only a few places, among them Northland, the hills behind Days Bay on Wellington Harbour and the Denniston Plateau in Westland.
To fundraise for Mr Wheatley's research and travel expenses, Moths and Butterflies NZ has started a Givealittle page called The Forest Ringlet Butterfly Project.
The trust is also screening the 3D film Flight of the Butterfly next Tuesday evening at Kerikeri's Cathay Cinema.
Tickets can only be bought through the trust's website: mb.org.nz/movie