A parasitic wasp from Tasmania has been introduced to attack caterpillars that damage eucalyptus trees.
The Cotesia Urubae wasp from Tasmania will act as a biological control agent to kill the gum leaf skeletoniser moth, whose larvae feed on the leaves of eucalypts trees causing significant damage and losses of trees and timber.
The Australian gumleaf skeletoniser is a particular pest in Auckland, but is also found through the top of the North Island, and last week turned up in Nelson.
In Auckland on Tuesday, 57 parasitic wasps were released by the Crown Research Institute, Scion.
The tiny insects, 3mm long, resemble mosquitos or small flies.
An insect scientist at Scion, Dr Lisa Berndt, says the wasp is so tiny that most people will never see it, and does not sting people.
The caterpillars it's hoped the wasps will target have venom in their hairs and can inflict a painful rash.
Dr Berndt says the wasp will be closely monitored and more releases are planned around the rest of the country.
The Forest Owners Association has welcomed the introduction of the wasp because of the damage the gumleaf skeletoniser can do to eucalyptus plantations.
There are almost 25,000 hectares of eucalypt forests in New Zealand.
Farm Forester Association spokesperson Denis Hocking says while New Zealand isn't a major producer of hardwoods, such as eucalypts, it is trying to expand production.
He says the release of the parasitic wasp is a good example of collaborative biocontrol work in New Zealand.
The Environmental Risk Management Authority approved the wasp in July, to act as a biological control agent.