American dagger moth
Its yellow caterpillar carries slender black hair pencils and hollow bristles that release an itch causing chemical if they break off in skin.
| Where | Deciduous woodlands, yards and parks |
|---|---|
| Size | 50 to 65 mm wingspan |
| When | June to October |
The adult is a fairly large, powdery gray moth with darker zigzag lines across the forewings and a pale ringed spot near the center of each wing. It is the largest dagger moth in the eastern United States, with a wingspan of 50 to 65 mm.
The caterpillar is pale yellow with long, dense hairs and four or five slender black pencils of bristles rising from its back. If handled, the brittle hairs can break off in skin and release a chemical that causes a burning, itchy rash lasting a day or two.
Traits
Habitat
Woodland
Colour
Yellow, Black, Grey
Active
Night
To people
Mild
The caterpillar's loose hairs can break off in skin and cause a stinging, itchy rash that usually clears within a day or two.
Activity through the year
Often confused with
A smaller, paler relative with a wingspan of about 40 to 50 mm and a mostly pure white forewing marked with fine black dashes, lacking the sharp double postmedian line of the American dagger moth.
Questions
Is the American dagger moth dangerous to people?
Mild. The caterpillar's loose hairs can break off in skin and cause a stinging, itchy rash that usually clears within a day or two.
When can you see the American dagger moth?
The American dagger moth can be seen from June to October, at night.
Plate retouched from a photo by Teá Montagna, CC BY 4.0, iNaturalist Licence
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Butterflies and moths›Owlet moths›Acronicta
Last updated 2026-09-26. Every entry is checked against published sources.