Pine processionary moth

Thaumetopoea pityocampa

The caterpillar of this species could become a pest for humans and pine trees if it settled here. Its hairs can irritate our skin. Its taste for pine needles can weaken the tree.

About the pine processionary moth

Pine processionary moth larvae create large silken nests on pine trees. At night, they feed on pine needles.

Late in winter or early in spring, the caterpillars display an interesting social behavior. The entire colony forms a long procession, moving in a line one behind the other. The procession searches for a place underground to transform into moths (pupate).

This moth is a native of Europe, but has spread to the Middle East and North Africa.

Global distribution of the moth

World map showing distribution of pine processionary moth.

Why this is a problem for New Zealand

The caterpillars feed on pine needles close to their nests. They increase pine needle loss (defoliation), which weakens and disfigures the tree.

For humans, the hairs on this caterpillar cause skin irritation and allergic reactions. This can result in conjunctivitis and breathing problems. These hairs can stay in the environment for up to a year after the caterpillar has turned into a moth.

Map of New Zealand showing where the pine processionary moth could establish

How could it get here?

The insect pupae could get here in soil or other growing media like potting mixes. A pupa is the insect life stage between caterpillar and moth.

How to identify the pine processionary moth

The caterpillar

The caterpillar grows to 40mm long and has a black head.

When young, the caterpillar is a dull apple green colour. After its second moult, it gains reddish patches on each body section. These patches have hairs growing out of them.

 

end-to-end line of dark coloured caterpillars with bristles large round-shaped silken nest covered in multiple caterpillars
Left: A procession of the caterpillars. Image: CC 2.0 by Angel Torres
Right: A silken nest in a pine tree with caterpillars on it. Image: CC 3.0 by John Ghent, Bugwood.org

The moth

  • The female's wingspan is 36mm to 49mm.
  • The male's wingspan is 31mm to 39mm.
  • Both sexes have hairy bodies.
  • They have 2 sets of wings that are dull grey.
Adult moth. Image: CC 2.0 by Ben Sale

If you think you've found the pine processionary moth

 


Note: This information is a summary of the moth's global distribution and potential impacts on New Zealand.

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