The pine processionary (Thaumetopoea pityocampa) is a moth of the subfamily Thaumetopoeinae in the family Notodontidae, known for the irritating hairs of its caterpillars, their processions, and the economic damage they cause in coniferous forests. The species was first described scientifically by Michael Denis and Ignaz Schiffermüller in 1775, though it was known to the ancients, with remedies described by Theophrastus, Dioscorides and Pliny the Elder. Its processionary behaviour was described in 1916 by the French entomologist Jean-Henri Fabre. It is one of the most destructive species to pines and cedars in Central Asia, North Africa and southern Europe.
The species is notable for the behaviour of its caterpillars, which overwinter in tent-like nests high in pine trees, and which proceed through the woods in nose-to-tail columns, protected from predators by their severely irritating hairs.
The species is one of the few insects where the larva develops in winter in temperate zones. Global warming is causing the species to affect forests progressively further north. in his 77 AD book De materia medica, Pliny the Elder recorded a treatment for the resulting itching in his Natural History; Theophrastus had earlier recommended the medicinal plant elecampane (horse-heal) in oil and wine to treat contact with "pine larvae" in his Historia Plantarum.
The French entomologist Jean-Henri Fabre conducted a famous The study has been cited innumerable times by inspirational and religious speakers who view it as a metaphor for blindly following a leader or for confusing activity with accomplishment.<!--
Description
The adult is a stout furry moth which holds its wings like a tent over the body, in the manner of the eggar moths (Lasiocampidae). The adult is larger than the oak processionary, Thaumetopoea processionea, has a crescent marking on the wings (unlike the pale eggar moth; the oak processionary has an indistinct marking), and is found in coniferous rather than broad-leaved forests. The caterpillars are readily recognised by their processionary habit and their presence (with large silken nests and signs of defoliation) in coniferous woods. They are orange-brown and hairy with blue bands.
Distribution
The species is native to the southern Mediterranean area, North Africa, the Middle East, and southern Europe. It has been spreading northwards since the 1990s, assisted by climate change and by commercial activities including planting of host trees and transportation, and has reached Brittany, forests to the north of Paris, and Strasbourg in northern France.
Life cycle
thumb|Eggs on pine
Though most individuals of the species only live one year, some in high altitudes or more northern areas may survive for over two years. Each female lays an "enormous number"
thumb|Adult
The larva is a major forest pest, living communally in large "tents", usually in pine trees but occasionally in cedar or larch, marching out at night in single file (hence the common name) to feed on the needles. There are often several such tents in a single tree. When they are ready to pupate, the larvae march in their usual fashion to the ground, where they disperse to pupate singly on or just below the surface.
Behaviour
thumb|upright|Tent made by larvae in pine tree; [[frass collects at the bottom of the tent.]]
Shelter building
T. pityocampa is highly social. Throughout its life cycle, an individual makes several shelters, possibly for protection from predators; the larvae emerge to feed at night. The first of these is flimsy and temporary, but in the third instar, they build a permanent nest. Once the permanent nest is built, the caterpillars become foragers, staying in the vicinity of the nest. The nest has no openings, so caterpillars force themselves through the layers of the shelter. The waste from the larvae's diet falls as frass and accumulates at the bottom of the nest. and some individuals may have an allergic reaction. When stressed or threatened, fifth-stage larvae eject hairs shaped like harpoons, which penetrate all areas of exposed skin nearby and irritate them with an urticating protein.
Forestry damage
thumb|upright|Damage to conifer, showing bitten-off needles
The pine processionary is a major economic pest in coniferous forests in southern Europe, where the caterpillar is responsible for most of the defoliation seen in coniferous trees; outbreaks are somewhat cyclical, with a period of 7 to 9 years. Although pines are the most susceptible, other conifer trees such as larches are also vulnerable. The caterpillars can completely defoliate trees if large numbers are present.
Global warming is causing the species to affect forests progressively further north. It has for example been a pest of forests in Southern Europe since classical times, but it has already reached the north of France.
Artificial control
Efforts to control the pine processionary have included biological control using Bacillus thuringiensis, which is effective on eggs and first- or second-stage caterpillars (in September or October), or insecticides such as diflubenzuron, an insect growth regulator, which can be sprayed from aircraft. Monitoring can include the use of pheromone traps. Other methods that have been tried include insecticides in oil inserted directly into nests, and mechanical removal of nests.
<gallery class="center" mode="nolines" heights="185px" widths="185px">
File:Trap Navarra.JPG|Synthetic pheromone trap, Spain, 2012
File:Écopiège à chenille processionnaire.JPG|"Ecological trap" for processionary caterpillars, France, 2014
File:Cartucho contra la procesionaria (cropped).JPG|Cartridge of the Spanish forest pest service, to be fired into pine processionary nests, 2016
File:El Ayuntamiento pone en marcha un plan de choque contra la procesionaria 01 (cropped).jpg|Madrid City Council workers in protective clothing cutting pine processionary nests, 2019
</gallery>
See also
- Oak processionary
Notes
References
External links
- Wildlife in France: Pine processionary moth