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Unicorn Caterpillar

Schizura unicornis (now placed in Coelodasys by iNaturalist)[5]

The unicorn caterpillar is the larva of a native prominent moth; it feeds alone on the leaves of many broadleaf trees and shrubs, and its mottled body with a horn-like hump looks like part of a chewed leaf edge.[1][4][2]

Group
Insect
Order
Lepidoptera
Family
Notodontidae
US records
41 states
Sources
5 cited
Updated
2026-10-17
Unicorn caterpillar, mottled brown with a horn-like hump, on the chewed edge of a leaf
Unicorn caterpillar, mottled brown with a horn-like hump, on the chewed edge of a leaf. (c) christine123, some rights reserved (CC BY) — via iNaturalist, CC BY 4.0
On this page
  1. Identification
  2. Look-alikes
  3. Where it lives
  4. Biology
  5. Damage and signs
  6. Health risk
  7. Control
  8. Related profiles
  9. Common questions
  10. Sources

How to identify it

  • Caterpillars are mottled brown and tan along the body, with a mottled brown head and a bright green patch on the second and third segments behind the head.[1][2]
  • A prominent horn-like hump rises from the first abdominal segment, with a smaller one near the tail.[1][2]
  • The moth is medium-sized, about 2.4 to 3.5 cm across the wings, maroon to purplish gray with pale greenish patches when fresh and a thin black bar in the middle of the forewing.[4][3]

Look-alikes

Look-alikeHow to tell them apart
Other prominent mothsRelated species in the same genus look similar as adults; the University of Alberta museum points to Schizura leptinoides and S. ipomoeae.[4]

Where it lives

Found in southern Canada and the United States east of the Rocky Mountains.[3]

US map: public records from 41 states since 1990 (GBIF).

Biology and life cycle

There is one generation a year in Missouri, with caterpillars present from summer to fall; in Alberta adults fly from late May to August and caterpillars feed from June through August.[1][4]

The caterpillars feed alone rather than in groups.[4]

Damage and signs

  • Hosts include apple, elm, aspen, willow, hickory, birch, cherry, dogwood, hawthorn, maple, poplar, oak and ironwood, among other broadleaf trees and shrubs.[1][3]
  • The University of Illinois lists it among caterpillars that look unusual but are not destructive.[2]

Health risk

None of the sources reports any harm to people or pets.[1][2]

Control

Prevention

Control isn't normally needed; the University of Illinois groups it with nondestructive caterpillars.[2]

Common questions

What is the brown caterpillar with a green patch and a horn on its back?
A small caterpillar with a horn-like hump just behind a bright green patch, mottled brown elsewhere, is likely a unicorn caterpillar.[1][2]
Is the unicorn caterpillar harmful?
Not usually; it feeds alone on tree and shrub leaves and is considered nondestructive.[4][2]

Sources

  1. University of Missouri Extension, “Caterpillars in Your Yard and Garden (IPM1019), page 47: unicorn caterpillar.” extension.missouri.edu/publications/ipm1019/47 (accessed 2026-10-17)
  2. University of Illinois Extension, “Unusual Caterpillars (Home, Yard and Garden Pest Newsletter, August 15, 2001).” hyg.ipm.illinois.edu/pastpest/200115c.html (accessed 2026-10-17)
  3. North Dakota State University (North Dakota Moths), “Unicorn caterpillar, Schizura unicornis (North Dakota Moths, Hodges 8007).” ndsu.edu/ndmoths/ndmoths/names/8007.htm (accessed 2026-10-17)
  4. University of Alberta Museums, “Schizura unicornis species details (E. H. Strickland Entomological Museum).” search.museums.ualberta.ca/g/2-461 (accessed 2026-10-17)
  5. iNaturalist, “Coelodasys unicornis taxon page (order and family).” www.inaturalist.org/taxa/1373714 (accessed 2026-10-06)

Updated 2026-10-17. Built from sourced records. Spot an error? Tell us.