The American dagger moth has a wingspan of 50 to 65 mm (2 to 2.5 inches). It is gray to gray-brown with darker markings. It usually has a sharp, double postmedian line, with white in between the two lines. There is a black dash on the anal area of the fore wing. The hind wing is gray with a faint, darker gray median line in the male. The female is similar, except the hind wing is completely dark.
- Acronicta americana americana
- Acronicta americana obscura
- Acronicta americana eldora
The American dagger moth can be seen from April to September throughout its range. Caterpillars can be seen from July to October. It has one brood in the north and two to three broods in the south.
The young caterpillar is densely covered with yellow setae. The older caterpillar's setae are either pale yellow or white. All instars have thin, black setae on the first and third abdominal segments. On the eighth abdominal segment, there is one tuft of black setae. The caterpillar will reach a length 50 mm (2 inches). Caution should be taken in handling the caterpillar, as the hollow setae may break off in to human skin, releasing a toxin which can produce a rash.
- Acer sp. — maple
- Acer negundo — Box Elder
- Aesculus hippocastanum — Horse Chestnut
- Alnus sp. — alder
- Betula sp. — birch
- Carpinus caroliniana — American Hornbeam
- Carya sp. — hickory
- Castanea sp. — chestnut
- Cercis sp. — redbud
- Corylus sp. — hazel
- Fraxinus sp. — ash
- Juglans sp. — walnut
- Platanus sp. — sycamore
- Populus sp. — poplar
- Quercus sp. — oak
- Salix sp. — willow
- Tilia sp. — basswood
- Ulmus sp. — elm
- Covell, Jr., Charles V. (2005) [First published 1984]. Moths of Eastern North America. Martinsville, VA: Virginia Museum of Natural History. p. 82. ISBN 1-884549-21-7.
- "Species Page - Acronicta americana". Entomology Collection. Alberta, Canada: University of Alberta E.H. Strickland Entomological Museum. 2001–2010. Retrieved 12 August 2010.
- Bartlett, Troy; et al (16 February 2004). "Species Acronicta americana - American Dagger Moth". Bugguide.net. Retrieved 12 August 2010.
- Wagner, David L. (2005). Caterpillars of Eastern North America. Princeton, NJ: Princeton University Press. p. 324. ISBN 0-691-12144-3.
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