Imported beetles are being released at a test farm in the lower Kaimai Ranges on Tuesday.
The 65 adult green thistle beetles will act as a biological control agent for the Californian thistle, which is one of the most persistent weeds on New Zealand farms.
Bay of Plenty Regional Council says green thistle beetle larvae reduce the growth and survival rates of the thistle by feeding on their stems and leaves.
Senior pest plant officer John Mather expects the beetle population to increase to sufficient levels for re-distribution around the region, in the next three years.
Although the beetle has been introduced to farms in other parts of the country, it is the first time they've been released in the Bay of Plenty.
There was also been a release at a site in the Wellington region.