|Euproctis chrysorrhoea, upperside|
|Female underside with the tuft of brown hairs|
This species can be found throughout Europe. It is an invasive species in the US, having arrived in the USA in the 1890s on plants coming from Europe. Through the early parts of the 20th century is was present in much of coastal New England from Connecticut to Maine, but years of cold and wet spring weather reduced its extent to the coast and islands of Maine and also parts of Cape Cod.
The wings of this species are pure white, as is the body, apart from a tuft of brown hairs at the end of the abdomen. The brown coloration extends along most of the back of the abdomen in the male. In the female, the back of the abdomen is white, but the tuft of brown hairs is much bigger. The wingspan is 36–42 millimetres (1.4–1.7 in). The species flies at night and is attracted to light.
The larva is brown with red and white markings and is very hairy. These hairs provide protection for this species throughout its life cycle: the larva incorporates some into the cocoon within which it pupates; the emerging adult female collects some on its tail and uses it to camouflage and protect the eggs as they are laid. The species overwinters communally as larvae within a tough, silken tent. In areas where the species is abundant, these tents are a familiar sight, and can be seen on a huge range of plants (see list below).
Cicely Blair wrote a paper about the rash caused by the brown-tail moth caterpillar in 1979. It was found that the loose hairs break off as barbs and on contact with skin can cause rashes, skin irritation, headaches and breathing difficulties. The species should be handled using protective gloves at all stages of its life cycle. Shed hairs blow about, and can be tracked indoors on shoes, so rash can occur without direct contact.
The peculiarity of brown-tail moth's life history is that for 10 months of a year it is in the larval stage, overwintering as young larvae. The phenology of this pest may be summarized as follows:
- Pre-diapausing larvae: they emerge and feed gregariously in August after about three weeks of egg incubation.
- Diapausing larvae: as a response to shortened periods of daylight, larvae build communal winter nests in the fall, inside of which they overwinter.
- Post-diapausing gregarious larvae: they resume feeding in early April synchronized with bud break and still inhabit the winter nest as their resting place.
- Post-diapausing dispersive larvae: once larvae reach late instars, colonies break up and larvae start feeding independently. Larvae pupate in June after six to eight instars. Imagos appear about one month later; they do not feed, have a short lifespan, and lay their eggs in late July and early August.
The factors underlying brown-tail moth population dynamics are little understood and have been only thoroughly investigated by few researchers. They found that parasitoids, microsporidial disease and intraspecific competition were the most important mortality agents. In North America, the incidence of parasitism is the most important factor dictating the persistence of the exotic populations exclusively in coastal habitats. Knowledge concerning the role of plant factors is limited to larval performance and development on different host plants. With regard to weather factors, it is known that diapausing larvae are cold tolerant but susceptible to freezing by extreme cold. In North America, besides parasitism, cold temperatures may prevent the browntail moth from extending its invasive range from coastal to inland habitats. Intraspecific competition may also be implicated in brown-tail moth mortality, since in several populations survival was higher at low densities. During outbreaks browntail moth females show an increased fecundity.
This univoltine defoliator feeds on 26 genera of non-resinous trees and shrubs belonging to 13 different families. Considering that it is unusual for an insect to feed on members belonging to more than two different families, the polyphagy of this pest is remarkable. Brown-tail moth polyphagy, together with its tendency to reach outbreak densities, makes this species a major pest of hardwood forests; it may also attack fruit and ornamental trees. 
Recorded food plants
- Acer – maple
- Arctium – burdock
- Betula – birch
- Carya – hickory
- Castanea – chestnut
- Chaenomeles – flowering quince ('Japonica')
- Crataegus – hawthorn
- Cydonia – quince
- Fagus – beech
- Fragaria – strawberry
- Fraxinus – ash
- Geranium – cranesbill
- Gossypium – cotton plant
- Hippophae – sea-buckthorn
- Juglans – walnut
- Malus – apple
- Parthenocissus – Virginia creeper
- Plantago – plantain
- Populus – poplar
- Pyrus – pear
- Quercus – oak
- Rheum – rhubarb
- Ribes – currant
- Rosa – Rose
- Rubus – raspberry, etc.
- Rumex – dock
- Salix – willow
- Sambucus – elderberry
- Tilia – lime
- Trifolium – clover
- Ulmus – elm
- Vitis – grape
- Selami Candan, Zekiye Suludere, Fatma Bayrakdar Surface morphology of eggs of Euproctis chrysorrhoea (Linnaeus, 1758) Article (PDF Available) in Acta Zoologica 89(2):133-136 April 2007 - DOI: 10.1111/j.1463-6395.2007.00300.x
- Blair, Cicely P. (1979). "The browntail moth, its caterpillar and their rash". Clin Experimental Dermatol. 4 (2): 215–222. doi:10.1111/j.1365-2230.1979.tb01621.x. Retrieved 7 January 2016.
- Mabey, Richard; Marren, Peter (2010). Bugs Britannica (Illustrated ed.). Random House UK. p. 273. Retrieved 7 January 2016.
- Graham, Gillian (2015-07-23). "Got an itchy rash? Browntail moths out in force in Maine, spreading noxious hairs". Portland Press Herald. Retrieved 26 May 2016.
- Lissaman, Clare (2011). "Fight to halt toxic caterpillars". BBC News. Retrieved 7 January 2016.
- Fear over poisonous caterpillars BBC News 16 May 2007
- Forest Pest Insects in North America: a Photographic Guide
- Chinery, Michael Collins Guide to the Insects of Britain and Western Europe 1986 (Reprinted 1991)
- Skinner, Bernard Colour Identification Guide to Moths of the British Isles 1984
- Jaenike, J. (1990) Host specialization in phytophagous insects. Annual Review of Ecology and Systematics, 21, 243-273.
- Forestry Compendium (2005) Euproctis chrysorrhoea L. (Lepidoptera: Lymantriidae) Datasheet. [Online] Wallingford: CAB International.
- Fernald, C. & Kirkland, A. (1903) The Brown-tail moth, Euproctis chrysorrhoea: a report on the life history and habits of the imported Brown-tail moth. Wright and Potter Printing, Boston.
- Saccuman, G. (1963) Contributo alla conoscenza della Euproctis chrysorrhoea L. Bolletino del Laboratorio di Entomologia Agraria "Filippo Silvestri", 21, 271-322.
- Torossian, C., Torossian, F., Roques, L. (1988) Le bombyx cul brun: Euproctis chrysorrhoea, (1) Cycle biologique-ecologie-nuisibilite. Bulletin de la Societe d'Histoire Naturelle de Toulouse 124, 127-174.
- Kelly, P.M., Speight, M.R. & Entwistle, P.F. (1989) Mass production and purification of Euproctis chrysorrhoea (L) Nuclear Polyhedrosis Virus. Journal of Virological Methods, 25, 93-99.
- Frago, E., Selfa, J., Pujade-Villar, J., Guara, M. & Bauce, E. (2009) Age and size thresholds for pupation and developmental polymorphism in the browntail moth, Euproctis chrysorrhoea (Lepidoptera: Lymantriidae), under conditions that either emulate diapause or prevent it. Journal of Insect Physiology, 55, 952-958.
- Dissescu, G. (1964) On a new method of the forecast of the Brown-Tail Moth. Zoologichesky Zhurnal, 43, 1795-1799.
- Schaefer, P.W. (1974) Population ecology of the browntail moth, Euproctis chrysorrhoea (Lepidoptera: Lymantriidae). PhD thesis. University of Maine, Orono.
- Zeitgamel, Y.S. (1974) Population dynamics of Euproctis chrysorrhoea in the Central-Chernozem State Reservation. Zoologichesky Zhurnal, 53, 292-296.
- Sterling, P.H. & Speight, M.R. (1989) Comparative mortalities of the Brown-tail moth, Euproctis chrysorrhoea (L) (Lepidoptera, Lymantriidae), in Southeast England. Botanical Journal of the Linnean Society, 101, 69-78.
- Arevalo-Durup, P. (1991) Le nid d'hiver d'Euproctis chrysorrhoea L. (Lepidoptera: Lymantriidae) comme estimateur de population en milieu forestier. Ph.D. Toulouse: Université Paul Sabatier.
- Elkinton, J.S., Preisser, E., Boettner, G. & Parry, D. (2008) Factors influencing larval survival of the invasive Browntail Moth (Lepidoptera: Lymantriidae) in relict North American populations. Environmental Entomology, 37, 1429-1437.
- Frago, E., Pujade-Villar, J., Guara, M., Selfa, J. (2011) Providing insights into browntail moth local outbreaks by combining life table data and semi-parametric statistics. Ecological Entomology 36, 188-199.
- Elkinton, J.S., Parry, D., Boettner, G.H. (2006) Implicating an introduced generalist parasitoid in the invasive browntail moth's enigmatic demise. Ecology 87, 2664-2672.
- Pantyukhov, G.A. (1962) The effect of positive temperatures upon different populations of the brown-tail moth Euproctis chrysorrhoea L. and the gipsy moth Lymantria dispar L.. (Lepidoptera, Orgyidae). Entomologicheskoe Obozrenie, 41, 274-284.
- Pantyukhov, G.A. (1964) The effect of negative temperatures on populations of the brown-tail moth Euproctis chrysorrhoea L. and the gipsy moth Lymantria dispar L. (Lepidoptera, Orgyidae). Review of applied entomology. Series A, 54, 434-436.
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