Entomology Collection TitleImage Bugs Pinned
Species Page - Acronicta americana
Acronicta americana ->species page

E-mail this Page   
Print this Page   
Link to this Page   

scientific name    Acronicta americana    

common name     American Dagger Moth

Deciduous woodlands, shelterbelts and urban plantations.

Adults have been collected in Alberta from late June through mid-July.

A fairly large (5.0 - 6.2 cm wingspan) brownish grey moth with darker markings. The forewings are grey with darker lines and spots, and with the veins lightly lined with dark scales. The postmedian line is doubled and the interspace is white, forming a contrasting toothed band. The hindwing is pale grey-brown with a faint darker median line and veins in the male. The female is similar but darker, especially the hindwings which are sooty brown. The antennae of both sexes are simple. A. dactylina is similar, but is lighter powdery grey, with fewer markings and in particular lacking the doubled, white-filled postmedian band on the forewing, the median line on the hindwings, and the dark scales along the veins.

life history
The larvae are solitary defoliators on various deciduous trees, in particular maple and birch. They are covered in long white or pale yellow hairs, with several tufts of longer, black hairs. There is a single brood each year, which overwinter as pupae. They are never common enough in Alberta to be considered a pest. Most likely to be found associated with urban and shelterbelt plantings of Manitoba maple. The adults are usually attracted to light. The American Dagger-moth is primarily a species of the eastern hardwood forests. The southern ssp. eldora is paler with crisper markings and Alberta specimens from Medicine Hat have been assigned to this form by Bowman (1951). Bowman also listed May as the adult flight period, apparently in error as all specimens in his collection are labeled as collected in June-July.

Widespread but uncommon here at the northwestern edge of it's range.

diet info
In Alberta larvae have been collected on Manitoba maple (Acer negundo). other trees have also been reported as hosts elsewhere (see Rings et al. 1992 and Prentice 1962).

A species of the eastern hardwood forest, recorded west to southeastern Alberta, and south to UT, CO, TX, KS and GA. In Alberta, it has been collected mainly in the eastern aspen parklands and grasslands regions, north to Lloydminster. Reports of American dagger moths from further west in Alberta (Peace River and foothills regions) in Prentice (1962) are questionable and need verification.

quick link

Comments (12)Add New Comment

Betsy (2010-07-24)
I believe I may have found an American Dagger Moth in the caterpillar stage on July 24, 2010 in a region of South Eastern PA. I belive it to be a female as the yellow is a darker shade than most of the pictures I have seen.

Krisann (2010-07-28)
Our family found two American Dagger Moth caterpillars in Berks County, PA. Hopefully we can have them overwinter in our butterfly cage.

Cheri (2010-07-29)
Our family has also found an American Dagger moth caterpillar in Westmoreland County, PA. Looking for more info on it.

norman (2010-09-19)
found two specimens today (Sept 19, 2010) near Rush Point, MN 55080

Maria (2011-08-10)
Found this furry guy on my porch in Ct

Danielle (2011-08-24)
We found a caterpillar that resembles what everyone indicates as an american dagger moth. We setup a habitat for it, and the day after we awoke to it being in a cocoon. Now our questions is - how long does it stay in a cocoon before hatching?

Felix Sperling (2011-08-31)
It will probably stay in a cocoon all winter, then will hatch in the late spring. If you look at the adult seasonal distribution histogram, you''ll see that the adults fly starting in May. So you could put the pupa outside for the winter, under natural conditions (perhaps in a jar in the garden) because if you leave it indoors it will probably dry out.

chloe berger (2011-09-21)

Chloe my 4 year old found what looks like a american dagger caterpillar. It is yellow fuzzy with the black longer hairs. Anyway what should we feed this guy its getting cold Sept 21st New Berlin, WI we have many Maples ready to shed leaves??? Isn''t it a little late to be a caterpillar?

Wiggers (2011-10-06)
I found the yellow caterpillar running on my shirt last Sunday. Place: Hooglanderveen, The Netherlands!!!! It for sure is not endemic in my country.

Lily and Josie (2015-08-16)
Found American Dagger Moth caterpillar in West Philadelphia, 8.16.15.

Hoping to hatch in the spring

Shane (2015-08-21)
We found one today at lunch, south shore of Montreal, Quebec, Canada. Put in a small habitat, already a cocoon by 21:30. Placing in garden tomorrow, or if we keep it indoors, how do we avoid it drying out?

Jan Shadick (2016-09-24)
Found one in Saskatoon, September, 2016.

Comments are published according to our submission guidelines. The EH Strickland Entomological Museum does not necessarily endorse the views expressed.

Add New Comment (all fields are required)

Related Species Info
Display Hierarchy
Specimen Info
There are 20 specimens of this species in the online database
Map Distribution
Adult Seasonal Distributioncreate a collection histogram with specimens
Specimen List (20)
Related Links
Moth Photographers Group


Logo Department of Museums and Collections ServicesLogo University of Alberta