A native moth which until now has been relatively benign is causing widespread havoc across North Island plantain crops.
AgResearch says reports have been coming in since early December from farmers reporting crop damage, with some losing up to 90 percent of their plantain.
Plantain - scientifically known as Plantago lanceolata is a robust herb suited to pastures, with a tap root that gives some drought tolerance, but it offers feed quality similar to ryegrass.
Senior scientist, Alison Popay says very little is known about the moth except that now more plantain is being planted, it has become more apparent.
"It can be totally devastating to plantain crops and completely wipe them out. It seems to affect second year crops more than first year crops because the moth population builds up".
Dr Popay says research is really only just starting on the plantain moth.
"We are still building up information on its life cycle and the build up in crops and potentially look at management to try and control it".
Dr Popay says the moths aren't causing problems south of Manawatu and she puts this down to the cooler climate.
The moth is called Scopula rubraria, or more commonly, plantain moth.
They are small, less than 20mm wide, light brown with darker spots and a distinct darker brown band towards the end of the wings.