Other Common Names
Unicorn Caterpillar (larva)
Unicorn Prominent (adult)
Variegated Prominent (adult)
Explanation of Names
UNICORNIS: from the Latin "unus" (one) + "cornu" (horn); the larva has a prominent fleshy "horn" projecting from the top of the first abdominal segment
Identification
Adult: forewing dark gray, variably shaded and marked with yellowish, rose, and brown, especially along costa and beyond PM line; basal area green (fading to whitish), bounded by double black AM line; reniform spot marked by black line; usually a black costal patch near apex, sharp black spots in ST area, and a white dash or spot near anal angle; usually holds wings in a "tent" position, sometimes partly rolled around body, and often rests in head-down position
hindwing dirty white, shaded with gray in male; dark gray in female
[adapted from descriptions by Charles Covell and Lynn Scott]
Larva: head mottled brown with diffuse black line from antenna to vertex; second and third thoracic segments bright green; remainder of body brown, with prominent hornlike protuberance on first abdominal segment, and smaller one on eighth abdominal segment; fifth abdominal segment not appreciably larger than A4 or A6
Range
all of North America except the arctic (absent only from Nunavut, Northwest Territories, Yukon, and Alaska)
Habitat
deciduous woodlands and shrubby areas
Season
adults fly from April to September in the south; May to August in the north
larvae May to October in the south; June to September in the north
Food
larvae feed on alder, apple, Trembling Aspen (Populus tremuloides), White Birch (Betula papyrifera), elm, hawthorn, hickory, willow
Life Cycle
one generation per year; overwinters as a larva beneath leaf litter in flimsy cocoon within which it pupates in spring
Remarks
Caterpillars in this genus are unusual in that they can eject a stream of formic acid for up to several inches from a gland in the hump. (U. of Alberta)
See Also
Schizura leptinoides (Black-blotched Prominent) and
S. ipomoeae (Morning Glory Prominent). Compare images of
all three species.
Internet References
live adult images plus description, food plants, flight season (Lynn Scott, Ontario)
live images of eggs, larva, adult plus biology, habits, food plants, seasonality, common name reference [Unicorn Prominent] (Jeremy Tatum, Butterflies and Moths of Southern Vancouver Island)
pinned adult image plus common name references [Variegated Prominent, Unicorn Caterpillar Moth], description, habitat, seasonality, food plants, distribution, habits (G.G, Anweiler, U. of Alberta)
pinned adult image and US distribution map (Paul Opler, Moths of North America; USGS)
pinned adult image (A.W. Thomas, Canadian Forest Service)
live larva image plus description, seasonality, life cycle (David Wagner and Valerie Giles, Caterpillars of Eastern Forests; USGS)
live larva image (Robert Anderson, USDA Forest Service)
live larva image on Swamp Rose (Bastiaan Drees, Texas A&M U.)
