Pine Processionary Moth - Thaumetopoea pityocampa

Scientific Name: Thaumetopoea pityocampa

English Name: Pine Processionary Moth

French Name: les Processionnaires du pin (='pine processionaries')

Caterpillar nests in a pine tree in a garden
near Charnizay photographed in March.
5 Key Characters:
  • hind wings white.
  • caterpillars move around together in long single file lines.
  • always in or near pine woods.
  • caterpillars dark with tufts of brown hair.
  • caterpillars live communally in silk nests on pine branches.
Lookalikes: Oak Processionary Moth T. processionea, however these are only associated with oak woods, not pine and the moths have discoloured hind wings. Don't confuse with other very hairy caterpillars such as the Garden Tiger Arctia caja.

Habitat: Pine trees and the ground nearby. The caterpillars seem to choose open ground to bury themselves for pupation.

Flight Period: May-June-July.

Caterpillar: Live in nests from autumn to spring. Every evening unless very cold the caterpillars emerge in single file to feed on pine needles. They are a serious pest of pine forests. One day in late spring they form a single file procession behind one of the female caterpillars. They descend from the tree and the female leads them to a patch of ground where they will bury themselves in the earth to pupate. Forestry managers have discovered that they can be tricked into thinking groves of deciduous trees planted amongst the conifers are open ground suitable for pupation. The trees come into leaf after the caterpillars pupate, leaving them in the shade and many of them die. The caterpillars have extremely irritating hairs which hang in the air and fall from the nests long after the caterpillars have vacated. Neither the nests nor the caterpillars should be handled, and pet owners need to be on their guard in case animals are exposed to irritant hairs. The rash generally lasts about 3 weeks and should be treated initially by taking a hot shower as soon as possible after exposure, and washing clothes exposed in hot water. Pets which are exposed should be seen by the vet as soon as possible, as in severe cases, exposure can lead to necrosis of the tongue, requiring amputation or even causing death.

Host Plant: All types of conifers with Black Austrian Pine being the preferred host.

Status: Increasingly common.

Further Information:
The great French naturalist Jean-Henri Fabre wrote about this species. A translation into English of his observations can be read here. They are informative, detailed, charming and fascinating.

Photographed by Loire Valley Nature:

Photographs are numbered from left to right, top to bottom. 1 rash caused by the caterpillars hairs. This is a moderately sensitive person who came into contact with the hairs by picking up a cat which had been outside in the vicinity of caterpillar nests and had collected hairs off the ground or floating in the air in its fur. 2 - 5 a caterpillar procession near Chaumussay, April.

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