Identifying Pine Processionary moth

As the days draw in and Christmas inevitably begins to loom on the horizon, hundreds of thousands of Christmas trees will soon be freshly cut in Europe and freighted over to the UK.  Although unlikely to be encountered, readers should keep a watchful eye out for signs of Pine Processionary Moth (PPM).

Originally from the Mediterranean, but now well established in Brittany and the north of Paris, this moth / caterpillar is a notifiable pest in the UK and poses human health risks. Similar to Oak Processionary Moth, which caused widespread disruption to public spaces in Europe over 2019, the Pine Processionary Moth caterpillar has hairs which are toxic to humans and animals, causing painful rashes and breathing difficulties… Not something you would want to put on your Christmas list or invite into your home over the holiday.  The main tree species utilised by PPM are Pines, Cedars and Larch – not classic Christmas Tree choices such as Norway Spruce or Nordmann Fir. However, Pines can occasionally be seen for sale as Christmas trees and PPM has been found on Douglas Fir and other conifers, particularly when the caterpillars are at their mobile stage just before Christmas. PPM caterpillars also burrow into the ground 10-20cm deep when it is time to pupate into moths, so can be transported in the soil of potted Christmas trees grown near infested trees abroad.

What to look out for

In the lead up to Christmas, PPM caterpillars will be feeding on the needles of host trees, before starting to build white silken ‘candy floss’ nests in the tree tops. Look out for hairy, ‘tiger-stripe’ caterpillars in particular, as these are less likely to be picked up in quality checks than defoliation and the white silken nests.

What to do

  • Buy UK grown Christmas trees as the pest is not established in the UK
  • Ask your Christmas tree seller what species the tree is
  • Ask your Christmas Tree seller if the trees are imported, or have been stored with imported trees
  • If you suspect PPM, immediately notify the Forestry Commission via TreeAlert and quarantine the tree(s) as best possible. Although the website may appear somewhat arms-length, it is a hot line to the Forest Research Centre at Alice Holt. LINK https://www.forestresearch.gov.uk/tools-and-resources/tree-alert/

What not to do

  • Do not touch or disturb caterpillars and their nests
  • Do not ignore the problem and allow the pest to establish in the UK.

What do we do?

All our Christmas trees come from the Oxford Christmas Company, who are based here at Nicholsons over Christmas. We interviewed their director, Lisa Fitzgibbon-Smythe, to obtain answers to the questions above.

Are your trees grown in the UK? Yes, in Norfolk and Berkshire. These farms are logistically closer and the trees are fresher (cut later) if they don’t have to travel from Scotland or Europe.

What tree species are they? Mostly Nordmann Fir, some Norway Spruce and Blue Spruce (pots).

Do they get stored with imported trees? No, they do not.  We have chosen growers very carefully that do not import trees from Europe. All of our trees are British-grown.

Do they get checked for pests and diseases at various stages of growth / your buying process? Yes, the trees are very carefully monitored by the farmers that grow them. They have teams of workers who regularly prune, mulch and care for the trees at the plantation. We visit the plantation twice a year to see the fields and the stock for ourselves. Some years there is more growth than others, depending on the weather, and occasionally if we have a very hot summer (like 2018), the new growth can burn and singe, giving the needles a reddish tinge.  During our visit this week, we were happy to see a lot of fresh, thick, healthy growth on the trees.  

Do the trees travel in their own lorry to get to Nicholsons, or do they share with other trees? Our suppliers deliver our trees in smaller lorries, so we get two deliveries rather than one big one.  This is better for the trees, as they do not get squashed into large articulated lorries. It also means that we do not share the delivery space with any other suppliers.  The trees are loaded at the plantation and are sent straight to us at Nicholsons. 

Identifying Pine Processionary moth
Identifying Pine Processionary moth

Photos by Ian Wallman

Identifying Pine Processionary moth