Orgyia pseudotsugata, the Douglas-fir tussock moth, is a moth of the subfamily Lymantriinae first described by James Halliday McDunnough in 1921. It is found in western North America. Its population periodically irrupts in cyclical outbreaks. The caterpillars feed on the needles of Douglas fir, true fir, and spruce in summer, and moths are on the wing from July or August to November.
| Douglas-fir tussock moth | |
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| Adult male | |
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| Adult female | |
Scientific classification 
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| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | Insecta |
| Order: | Lepidoptera |
| Superfamily: | Noctuoidea |
| Family: | Erebidae |
| Genus: | Orgyia |
| Species: | O. pseudotsugata
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| Binomial name | |
| Orgyia pseudotsugata (McDunnough, 1921)[1]
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| Synonyms | |
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Description
editAdult males are grayish brown moths with mottled light and dark markings. The males' wingspread is 25–34 mm (0.98–1.34 in). When the wings are spread open, the brown hindwings can be seen. Individuals in the northern part of its range are darker and southern populations are lighter. Antennae are plumose (feathery). Females are flightless with only rudimentary wings. Larvae (caterpillars) are 20–26 mm (0.79–1.02 in) and colorful with red spots, white spines, conspicuous red-tipped white tufts or "tussocks", and dense bunches of long, black hairs projecting to the front and behind.[2][3][4][5]
Range and host plants
editThe Douglas-fir tussock moth is native to forests of western North America and outbreaks have been identified in British Columbia, Idaho, Washington, Oregon, Nevada, California, Arizona, and New Mexico.[5] Outbreaks occur in cycles around eight to twelve years and usually last up to four years, sometimes longer. Reports from Idaho and Washington indicate 2011 had a major outbreak.[4][6] The larvae feed on Pseudotsuga and Abies species, especially Douglas fir, grand fir, white fir, and subalpine fir.[5][7]
Life cycle
editEggs hatch in spring (May to June) and the young larvae begin feeding on new foliage (the current season’s growth of needles). Later, they feed on both new and old foliage. The movement of the caterpillars is the main means of biological dispersal. They produce long, silky threads which can catch the wind when they drop from one branch to another. They produce loose webbing which forms a netting. In this cocoon, they pupate in July or August. Adults emerge and are active as late as November. The flightless females stay near the cocoons from which they emerged and mate straight away. Eggs are spherical and white and are laid in a mass which protects them through winter.[2][5] Because the female is sedentary, population outbreaks always form in place.[8]
Management
editOne key to management of outbreaks is detection. Entomologists monitor forests using an early warning system of pheromone traps.[8][9][10] Outbreaks subside on their own, but silvicultural techniques for managing affected timber can be employed,[4] or the chemical carbaryl can be sprayed aerially.[5]
Subspecies
edit- O. p. pseudotsugata (British Columbia to Idaho, western Montana, eastern Washington, Oregon, Colorado, Nevada, California)
- O. p. morosa Ferguson, 1978 (British Columbia to California)
- O. p. benigna Ferguson, 1978 (Arizona)
Gallery
edit-
Eggs -
Larva -
Damage -
Damage -
Cocoon -
Pupa -
Moths emerging from pupal cases on side of building -
Adult female and male
References
edit- ^ "Moth Photographers Group". Mississippi Entomological Museum at Mississippi State University. Retrieved 2 October 2011.
- ^ a b McLean, John A. (10 February 1997). "Douglas-fir Tussock Moth, Orgyia pseudotsugata, in British Columbia". University of British Columbia Forestry. Retrieved 2 October 2011.
- ^ Balaban, John and Jane; Davis, John; Hardy, Randy (5 February 2011). "Species Orgyia pseudotsugata - Douglas Fir Tussock - Hodges#8312". BugGuide. Retrieved 2 October 2011.
- ^ a b c "Douglas-fir tussock moth (Orgyia pseudotsugata) defoliation in Kootenai and Benewah Counties" (PDF). Idaho Department of Lands. Archived from the original (PDF) on 25 April 2012. Retrieved 2 October 2011.
- ^ a b c d e Wickman, Boyd E.; Mason, Richard R.; Trostle, Galen C. (30 April 1998). "Douglas-Fir Tussock Moth". Forest Insect & Disease Leaflet 86. United States Forest Service. Retrieved 2 October 2011.
- ^ Kramer, Becky (17 August 2011). "Tussock moths' impact on fir trees visible". The Spokesman-Review. Spokane, WA. Retrieved 2 October 2011.
- ^
Dekker-Robertson, Donna; Griessmann, Peter; Baumgartner, Dave; Hanley, Don. "Douglas-Fir Tussock Moth (Orgyia pseudotsugata)". Forest Health Notes. Washington State University Cooperative Extension.
{{cite web}}: Missing or empty|url=(help) - ^ a b "Douglas-fir Tussock Moth, Orgyia pseudotsugata". Decayed Wood Advisor. United States Forest Service. Retrieved 2 October 2011.
- ^ "Douglas-fir tussock moth (Orgyia pseudotsugata): Outbreak status of a conifer defoliating caterpillar" (PDF). Washington Department of Natural Resources. 31 December 2010. Retrieved 2 October 2011.
- ^ "Douglas-fir Tussock Moth Outbreak". National Park Service. 17 December 2008. Retrieved 2 October 2011.