Pine processionary moth: what the agencies record

This page reports what the official source says. It is not legal advice: ask the office named here. It does not identify what is wrong with any tree and does not say what should be done about one. The pine processionary moth, Thaumetopoea pityocampa, is a southern European moth whose caterpillars feed on pine needles. Forest Research lists it as not present in the United Kingdom and notifiable. Each section names its source, all read on October 9, 2026. The parent page, insect pests of trees, compares it with the other pests on the list, and a close relative has its own page on the oak processionary moth.

Names and where it comes from

Forest Research, the research agency of the Forestry Commission, says the moth is native to southern Europe, North Africa and parts of the Middle East. Like the oak processionary moth, it is named for the caterpillars' habit of moving in nose-to-tail processions. Forest Research says the range has been extending northwards with the international trade in live plants, and that the moth is established as far north as Hungary, Switzerland and the Paris region. It lists the countries where it is recorded as established: Albania, Algeria, Austria, Bulgaria, Croatia, Cyprus, France (including Corsica), Greece (including Crete), Hungary, Italy (including Sardinia and Sicily), Libya, Macedonia, Montenegro, Morocco, Portugal, Serbia, Slovenia, Spain (including the Balearic Islands), Switzerland, Syria and Tunisia.

Host trees

Forest Research says trees of the genus Pinus are the most susceptible, and names Austrian pine, Aleppo pine, Canary Island pine, lodgepole pine, maritime pine, Monterey or radiata pine, Scots pine and stone pine as particularly susceptible. It adds Atlas cedar and European larch as other recorded hosts. The Forestry Commission contingency plan, dated August 3, 2022 in its page footers, says hosts include Pinus and Cedrus species and that the moth has also been seen on Larix and Pseudotsuga. Forest Research notes that Scots pine is the only native pine in the United Kingdom, and that European larch, Scots pine and lodgepole pine are widely grown there. The agency profiles for two of the host species are on the pages for lodgepole pine and Monterey pine.

Signs and life stages as the sources describe them

Stage or sign	What Forest Research records
Nests	White silken nests built in the foliage and small branches from about January, up to the size of a football, with several nests possible in one tree; they degrade and discolour over time
Caterpillars	Hairy, orange-brown with blue bands, in nose-to-tail processions on the trees or on the ground in winter and early spring; they stay in the nests by day and feed at night
Damage to the tree	Loss of needles; complete defoliation is possible where infestation is heavy
Moths	Cream forewings with brown markings and white hindwings, flying from about May to July; Forest Research says they are hard for an untrained observer to tell from other species

Forest Research sets out how it differs from the oak processionary moth. The pine moth's caterpillars are more likely to form a single-file procession, are found on pine or other conifers, build nests among the needles and small branches, have dense clumps of hairs with little variation in length, and are seen in winter and early spring. The oak moth's caterpillars often form a wedge, live on oak, nest on trunks and larger branches, have very long white hairs, and are seen in late spring and early summer.

Life cycle

Forest Research gives the cycle as follows. The adults live for about a day in summer, mate and lay eggs in pine trees. The caterpillars hatch in autumn and start to feed on needles. From about January they live in the silk nests, and in early spring they leave in processions and pupate in the soil until summer. The pupal stage can stay dormant for another year or two, which stretches the cycle over two or three years. The contingency plan says positive identification can only be made in a laboratory, from the shape of the insect or DNA sequencing.

How it spreads

Forest Research names two routes: the movement of plants for planting, and natural spread. It judges larvae arriving on imported plants to be mitigated by the fact that plants are usually imported in winter and spring, when the nests are obvious, and judges egg masses on plants to be a low risk. It says pupae could arrive in the soil of host plants, can stay in the soil for up to three years, and are unlikely to be found by inspection; this is the route believed to have taken the moth to the Paris area. For natural spread it gives an average female flight of 1.7 km, a maximum recorded of 10.5 km, and a recorded rate of spread of 5.6 km a year in the area south of the Paris Basin.

Health effects as the sources record them

Forest Research says the caterpillars carry thousands of tiny hairs holding an irritating protein, thaumetopoein, which can cause painful skin, eye and throat irritation and rashes, and in rare cases allergic reactions. The contingency plan lists skin problems, conjunctivitis, respiratory congestion and asthma, and says the hairs can detach and be carried on the wind, so direct contact is not needed. Forest Research says the adult moths are harmless to people and animals. The Forest Research page lists precautions for people, pets and livestock; this page does not repeat them as advice.

Where it is reported in the United Kingdom

Forest Research says there are no known established populations in the United Kingdom. Single moths have been found in southern England, in 1966 (a light trap in Berkshire, origin unknown), in August 2013 and in summer 2017, the last two on the south coast and probably blown across from France. A transient population of larvae was found in a nursery in 1995 on Scots pine plants imported from Italy in 1994; the trees and soil were treated and later monitoring found no more. The Forestry Commission plan records a Defra rapid pest risk assessment of December 2015 that judged it possible for the moth to establish in the United Kingdom, with colonies likely to be limited to Cornwall, the south coast of England, coastal Pembrokeshire and London.

Regulated status and reporting

Source	What it records
Forest Research	The United Kingdom has had European Protected Zone status for the moth since 2017, so imported pine plants need a plant passport certifying a moth-free place of production, area or country, and pending landings of pine plants must be notified for inspection. A surveillance programme monitors pines in the wider environment, and the status is conditional on the moth not turning up widely.
Forestry Commission contingency plan	The plan sets an initial regulated area of at least 2 km around infested trees, with movement of host plants, pine plants for planting and soil prohibited out of it, and says the first aim would be eradication, with containment if that proves impossible. The plan text also says the moth was not listed in the European plant health directive, and it carries a last-updated note of March 2016.
EPPO Global Database	Categorization: United Kingdom, A1 list, added 2020; European Union, protected-zone quarantine pest under Annex III of Regulation (EU) 2019/2072, added 2019; China, quarantine pest, 2021; Argentina, Brazil, Chile and Iran, A1 lists, 2018 to 2019; COSAVE, A1 list, 2018.

Forest Research asks that suspected sightings in Great Britain go to the TreeAlert reporting tool, and in Northern Ireland to the all-Ireland TreeCheck tool, each with at least one clear photograph. It lists the plant health offices for suspected sightings on plants in trade, and says it does not need reports of adult moths. See reporting a pest in the United Kingdom for the offices. How Great Britain regulates the oak moth, zone by zone, is on its own page.

Management as the sources list it

Forest Research and the contingency plan both describe the response to an outbreak outside trade premises as eradication first, using Statutory Plant Health Notices on tree owners, with treatment options of insecticide applications at the larval stage and nest and caterpillar removal, which Forest Research says trained operators carry out. This page gives no product names, rates or timings. For who may apply pesticides, see pesticide licences.

The Forest Research material was read under the Open Government Licence v3.0 and is restated here in our own words.