Forest Research forest health adviser Chris Scott has now found a potentially serious pest of the coastal banksia, entomologist Toni Withers said in a statement today.

Stegommata sulfuratella is a moth from an insect family that does not occur in New Zealand, she said.

Banksia's yellow flowers are a valuable nectar source for many native birds, such as tui and bellbirds.

Painted apple moths, their larvae and egg masses were found in the West Auckland suburb of Glendene this month, sparking fears it could pose a huge risk to horticulture and forests.

Forestry workers found signs of that pest on only six properties and have been spraying with an organo-phosphate insecticide spray, with the most recent spraying on Saturday.

Stegommata sulfuratella caterpillars feed on the internal tissue of the banksia's young leaves creating a mine or tunnel. This can hollow out an entire young leaf.

The caterpillars are a pale green colour and up to 5mm long, as are the pupae. The pupae may be found held in silken hammocks strung inside the curled banksia leaves.

The adult moth is pure white but very small at less than 6mm long, which means that they will be hard to find.

Larvae have been found in Glendowie, in the eastern suburbs, in the western suburb of Mt Albert, at the Auckland Zoo, and in Glendene.

These locations suggest a widespread distribution within central Auckland, Dr Withers said.