Orgyia definita
Packard, 1865
Definite Tussock Moth, Definite-marked Tussock Moth
Orgyia definita is a in the Erebidae, to eastern North America. Males have functional with a wingspan of approximately 30 mm, while females are wingless—a distinctive trait shared with other Orgyia . The feed on a broad range of woody deciduous plants. The species was first described by Alpheus Spring Packard in 1865.
Pronunciation
How to pronounce Orgyia definita: /ˈɔr.dʒi.a dɛˈfɪn.ɪ.ta/
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Identification
Females are readily identified by their wingless condition, a trait shared with such as Orgyia antiqua and O. pseudotsugata. Males may be distinguished from similar Orgyia by or geographic range, though specific diagnostic features for O. definita males are not detailed in available sources. Larval identification to species level within Orgyia requires examination of morphological details not provided here.
Images
Habitat
Associated with deciduous forests and woodlands containing tree . Specific microhabitat preferences for are not documented.
Distribution
Eastern North America: from Minnesota east to New Brunswick, and south to South Carolina, Mississippi, and Louisiana. Records include Vermont.
Diet
feed on leaves of Salix (willow), Quercus (oak), Tilia (basswood), Ulmus (elm), Betula (birch), Acer rubrum (red maple), and Hamamelis virginiana ( witch-hazel). feeding habits are not documented.
Host Associations
- Salix - larval willow
- Quercus - larval oak
- Tilia - larval basswood
- Ulmus - larval elm
- Betula - larval birch
- Acer rubrum - larval red maple
- Hamamelis virginiana - larval witch-hazel
Life Cycle
with , , , and stages. Females lay eggs on or near their after calling males using . Detailed and number of per year are not documented.
Behavior
Females are sedentary and remain near their , emitting to attract flying males. This has been observed in and is characteristic of the .
Ecological Role
Larval on deciduous trees and shrubs. May serve as for , as documented for congeneric (e.g., Orgyia pseudotsugata parasitized by Pimpla sanguinipes).
Human Relevance
Not documented as a significant . The broad range of suggests potential for localized , but no economic or ecological impacts are reported in available sources.
Similar Taxa
- Orgyia antiquaAlso has wingless females and winged males; overlaps in general . Distinguished by geographic range (palearctic distribution for O. antiqua versus eastern Nearctic for O. definita) and larval coloration patterns.
- Orgyia pseudotsugataDouglas-fir , also with wingless females. Distinguished by primary association with conifers (Pseudotsuga, Abies) versus deciduous hosts for O. definita, and western Nearctic distribution.
- Orgyia vetustaWestern , also with wingless females. Distinguished by western Nearctic distribution and different larval preferences.
More Details
Taxonomic Note
The was described by Packard in 1865 (some sources cite 1864). It is classified in Lymantriinae, tribe Orgyiini. The wingless female condition is an of the Orgyia within Lymantriinae.
Observation Data
As of source date, iNaturalist records 8,874 observations, indicating the is relatively well-documented by citizen scientists within its range.