There are signs that a newly introduced wasp is taking hold in Auckland.
The Cotesia urabae wasp was released in the Auckland Domain in January as a means to control the gumleaf skeletoniser caterpillar, which defoliates gumtrees and can sting people.
The Crown Research Institute Scion says evidence has now been found that the wasp is reproducing.
Entomologist Michelle Watson says two cocoons have been found in the domain, which, she says, show the life cycle is being completed.
She says the wasp reproduces by laying eggs inside the caterpillars, so the presence of cocoons must also mean the caterpillars are being killed.