Sandra Coney releases the beetles with scientist Chris Winks of Landcare Research and Jack Craw, Manager Biosecurity Auckland Council Photo Alistair Jamieson

This is not exactly a Piha story but something I was involved in today 25 March that could be of great benefit to Piha where tradescantia is extremely common in forest in the residential areas.

Despite the rain, we gathered at Mt Smart (Rarotonga) Domain to release 300 tiny Peruvian beetles that hopefully will munch their way through the tradescantia (wandering jew or wandering willy) of the Auckland Region.

It has taken 8 years of research by Landcare Research in partnership with Auckland Council to test that the tiny beetles will eat only the target weed – tradescantia is the only plant they recongnise as food. This is the first release of the insect – or any biological control for tradescantia – worldwide.

Trandescantia is terribly harmful to forests. It completely smothers the forest floor up to several feet in depth and prevents the growth of successional seedlings. As the forest thins out, it allows other weeds to invade, such as Japanese honeysuckle and moth plant.

It is hard to eradicate manually as any little bit of broken stem will sprout, so that there are real risks of disposal of the weed. Taking tradescantia off sites may simply spread it into other areas. Spraying can be successful, but several treatments are usually needed.

The tradescantia leaf beetle