Other Common Names
Unicorn Caterpillar (larva)
Unicorn Prominent (adult)
Variegated Prominent (adult)
Synonyms and other taxonomic changes
Phalaena unicornis Smith, 1797
Schizura unicornis race deserta Barnes, 1929
Coelodasys edmandsii Packard, 1864
Edema humilis Walker, 1865
Edema semirufescens Walker, 1865
Phylogenetic sequence # 930100
Explanation of Names
Coelodasys unicornis (Smith, 1797), n. comb. in Becker (2014)
(1), was formerly placed in the genus
Schizura.
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
Canada: NL to BC; USA: Throughout eastern states west to WA, OR, UT and eastern TX in forested habitat
(2)
Type locality (unicornis): Georgia.
Type locality (race deserta): Stockton, UT.
Type locality (edmandsii): Cambridge, MA.
Type locality (humilis): North America.
Type locality (semirufescens): United States.
Habitat
deciduous woodlands and shrubby areas
Season
Bivoltine
on Block Island, RI, with adult records from mid-May through early September and peaks in abundance in June and August.
(3)Food
larvae feed on alder, apple, Trembling Aspen (Populus tremuloides), White Birch (Betula papyrifera), elm, hawthorn, hickory, willow
Life Cycle
overwinters as a larva beneath leaf litter in flimsy cocoon within which it pupates in spring
Larva; larva; birch leaf shelter; adult; inside of leaf shelter with spent pupa case
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.
Print References
Smith, 1797. in Smith & Abbot, Nat. Hist. Rarer Lepid. Ins. Georgia, 2: 171, pl. 86.