American Dagger Moth: All You Need to Know in a Quick Guide

The American dagger moth is a fascinating and unique species of moth native to North America. Known for its striking appearance and intriguing life cycle, these moths have captivated lepidopterists and casual observers alike.

Characterized by their yellow-white body and dark, dagger-like markings on their wings, adult American dagger moths are a stunning sight.

As caterpillars, they have a distinct appearance, sporting long, black bristles and soft yellow tufts.

American Dagger Moth
American Dagger Moth

These fascinating creatures can typically be found in deciduous forests, where their preferred food sources include the leaves of trees such as oak, maple, and willow.

Characteristics of American Dagger Moth

The American dagger moth (Acronicta americana) is a member of the family Noctuidae within the order Lepidoptera.

These caterpillars and moths are commonly found throughout North America.

A close relative of these moths that also resides in North America is the fingered dragon moth, whose caterpillars are similar in color and apperance.

Physical Characteristics

Caterpillar:

  • Covered in fuzzy hair-like setae
  • Yellow-green body with black markings
  • Approximately 2 inches in length

Moth:

  • Wingspan ranges from 2 to 2.5 inches
  • Grayish-brown wings
  • Black markings resembling daggers

Habitat

The American dagger moth can be found in a variety of habitats, including forests, urban areas, and where their host plants, such as boxelder maple and silver maple, grow.

In Colorado, they are generally distributed in areas where boxelder maple is present.

Table showing the habitat of the American dagger moth

RegionHost Plants
ForestsVarious trees
Urban AreasSilver maple
Boxelder Maple AreasBoxelder maple

Life Cycle and Behavior

The life cycle starts when adult moths lay eggs on the leaves of these trees. They have a distinct mating season that occurs during summer months.

Caterpillar

The American dagger moth caterpillar is known for its unique appearance, with features such as:

  • Green body
  • Long, black hair-like setae
  • Yellow bands around the body

These caterpillars feed on the leaves of deciduous trees, providing them with the energy they need to grow and eventually become adult moths.

Adult Moth

Characteristics of the adult American dagger moth include:

  • Wingspan: 50-70 mm
  • Setae on wings and upper legs
  • Faint black zigzag markings on wings

As adult moths, their behavior shifts from feeding on leaves to focusing on the reproduction process, which happens during the summer months.

Table showing the differences between the caterpillar and adult moth stages

Caterpillar StageAdult Moth Stage
Feeds on leavesReproduces in summer
Green body with setaeGrayish-white wings
Deciduous trees habitatBlack zigzag markings on wings

Is The American Dagger Moth Caterpillar Harmful?

The Is the American dagger moth caterpillar can cause skin irritation due to the venomous spines it has. When these spines come in contact with human skin, they can cause:

  • Burning sensations
  • Itching
  • Severe rash
  • Hematoma
  • Inflammation

These symptoms might occur soon after exposure to the caterpillar’s spines.

First Aid and Treatment

If you find yourself stung by an American dagger moth caterpillar, follow these first aid steps:

  1. Remove the spines: Use a piece of tape or tweezers to gently remove any spines stuck to your skin.
  2. Clean and disinfect: Wash the affected area with soap and water to avoid infection.
  3. Soothe pain and itching: Apply ice or a cold compress to reduce swelling and burning sensations. Over-the-counter creams or antihistamines can also help with itching.

Remember to seek medical help if symptoms worsen or don’t improve within a few days.

Pros and Cons of the American dagger moth

ProsCons
Plays an important role in the ecosystemCan cause severe skin irritation and rash
Non-aggressive to humansUnintentional stings can be painful

The American dagger moth is an important part of the ecosystem, but their venomous spines can lead to skin irritation and other symptoms if accidentally touched.

Proper first aid and treatment can help alleviate these symptoms.

Feeding Habits and Diet

The American dagger moth is a species known for its unique markings. One of its primary characteristics is its feeding habits, especially during the caterpillar stage of the insect’s life.

Caterpillars of the American dagger moth primarily feed on the leaves of various trees. Some common tree species they consume include willow, maple, alder, birch, American hornbeam, hickory, chestnut, poplar, oak, and basswood1.

Identification and Predators

The American dagger moth can be identified by its unique appearance. They have:

  • Yellow-green bristles
  • Grayish-white setae on wings
  • Upper legs with markings
  • Faint black zigzags on wings
  • Narrow black ring near edge of each wing

You can spot them by looking for their distinctive markings on the forewing that resemble daggers.

However, these moths are more than just interesting-looking creatures. They have natural predators which help keep their population in check. Some common predators include:

  • Birds
  • Bats
  • Spiders

When comparing this moth to others, you’ll notice the distinct double postmedian line and a black dash on its wings, which distinguishes it from its relatives.

While observing these creatures to avoid contact with their bristles, as they can sometimes cause irritation or an allergic reaction.

Tips for Dealing with American Dagger Moth Caterpillars

American dagger moth caterpillars can be a nuisance due to their irritating hairs. Here are some tips for dealing with them:

1. Consult an entomologist: If you encounter these caterpillars and need assistance identifying them or managing an infestation, consider contacting a local entomologist or extension office for expert advice.

2. Use tape to remove hairs: If you come into contact with the yellow hairs of American dagger moth caterpillars, gently use adhesive tape to remove them from your skin, as they can cause irritation and discomfort.

3. Use soap and water for washing: After coming into contact with the caterpillar hairs, wash the affected area with soap and water as soon as possible to minimize irritation.

4. Monitor for damage: While these caterpillars generally cause minimal damage to trees and plants, keep an eye on your garden and assess if any action needs to be taken.

5. Turn to natural predators: Encourage the presence of natural predators, such as birds and beneficial insects, in your garden to help control the caterpillar population.

6. Relocate caterpillars: If you need to remove and relocate the caterpillars, use protective gloves or tools like tweezers to limit direct contact with the irritating hairs.

7. Cultivate healthy soil: A healthier soil environment promotes plant resilience and may help reduce caterpillar populations over time.

Here’s a comparison of some methods for dealing with American dagger moth caterpillars:

Remember, if you’re unsure how to handle an American dagger moth caterpillar situation, it’s best to consult with a professional entomologist or local extension office for guidance.

Distribution and Conservation

The American dagger moth can be found in various regions across North America. They are more commonly spotted in states like Florida and Texas.

The conservation status of the American dagger moth is currently not a major concern. However, it’s essential to preserve the habitats that support their population.

American dagger moths play an integral role in their ecosystem. They are a food source for various predators, while their larvae feed on different host plants.

American dagger moths are an essential part of the food chain. They contribute to ecological balance, so it’s important to maintain this equilibrium.

Conclusion

The American dagger moth is a captivating and vital species native to North America.

While their venomous spines can cause skin irritation, proper first aid can alleviate the symptoms. As an integral part of the ecosystem, preserving their habitats is crucial for maintaining ecological balance.

By understanding and appreciating these unique creatures, we can ensure their continued presence in our natural world.

Footnotes

  1. American Dagger Moth | NC State Extension Publications

Readers’ Mail

Over the years, whatsthatbug.com has received hundreds of letters and some beautiful images asking us about American Dagger Moths (adult, pupa and larva). Scroll down to have a look at some of them.

Letter 1 – Many Banded Daggerwing from Mexico

Striped anglewing butterfly?
January 24, 2010
Thank you for your help in identifying this butterfly found in a jungle, mangrove area on yucatan peninsula in January, 2010.
F Parker
Puerto Morelos, Mexico

Many Banded Daggerwing

Dear F Parker,
This is a Many Banded Daggerwing, Marpesia chiron, a species, according to BugGuide, that ranges from “West Indies and Mexico south to Argentina. Rare stray to south Texas, very rare to Florida and Arizona, one record from Kansas.” 

We have previously posted photos of a related species, the Ruddy Daggerwing, but your photo is a first for the Many Banded Daggerwing.  Thanks for the contribution.

Letter 2 – Pansy Daggerwing from Costa Rica

Subject: Costa Rican Butterfly
Location: Tuis, CR – 2 hours east of San Jose, Costa Rica
February 2, 2013 4:24 pm
I took this picture near Tuis, Costa Rica a few weeks ago. I’ve been unable to identify it without buying a book.
Any help you can give me would be great.
Thanks!
Signature: Jody G

Pansy Daggerwing

Hi Jody,
This is surely a striking butterfly with a stunning color combination.  We did a web search for “orange purple butterfly costa rica” and quickly found this framed specimen on Etsy where it is identified as
Marpesia marcella.  We then searched that name and found a lovely photo on TrekNature where this information is posted: 

“This butterfly is relatively easy to find at the edges of rain forests and near rivers. It is usual to settle on the sand and sedimentary rocks, from which it seems to draw sales. Usually only found above 800 meters in elevation above the sea.”  Learn about Nature Butterflies of the Andes refers to it as the Pansy Daggerwing and states: 

“This species is usually encountered as small groups of up to about 6 males, visiting wet sand or mud to imbibe mineral-laden moisture. In hot weather the butterflies tend to constantly flit from spot to spot, fanning their wings, but occasionally settle for a while and feed while holding their wings erect. In cooler or shady conditions they feed with wings outspread.  Females are elusive, spending most of their lives in the forest canopy, but in overcast weather will sometimes descend to settle on foliage along forest trails.” 

Your individual appears to be puddling to derive moisture and minerals from the moist earth. 

Thank you so much! This is great. I’ve spent hours on every website I can find without success. I was just in your Carnage section. Too bad people don’t get it about spiders.  They are our friends (for the most part)!! And the glass and postcard trick works great.
Thanks again.
Jody

Letter 3 – Ruddy Daggerwing and Julia Butterflies Mating

Caterpillar ID
Hi,
I live in South Florida.
I’ve been ‘searching and squishing’ Tomato Hornworm caterpillars on my tomato plants for over a month now. (Resisting temptation to use poisons). I’m sending you a quite nice photo I took of one before the squish, in case you want it for your site. Today I found a large, superficially similar caterpillar on my fig tree. I know it’s not the same.

But what is it? I’m including two photos of the ‘fig caterpillar’. I suspect it’s a butterfly. I’ve included a photo of a pair of one species I found mating there, and two of another butterfly that spent a lot of time in the tree. The lone butterfly is a species I’d never even seen before.

The tree can well spare a few leaves, and there’s only one of these caterpillars as far as I can tell, so I’ve left it alone. I’m curious to know what it is and if you can identify the butterflies as well, that would be lovely.
Marian Mendez

Ruddy DaggerwingJulia Butterflies Mating


Hi Marian,
We are very excited to receive your letter and your wonderful photographs. Your single butterfly is a Ruddy Daggerwing, Marpesia petreus. They also have caterpillars that eat the leaves of figs. Your mating butterflies are Julias, Dryas iulia.

They are common in Florida. The host plant for caterpillars is the Passion Flower Vine. We will also be including this image in our new Love Among Bugs page. Also check out Marian’s Caterpillars.

Letter 4 – Ruddy Daggerwing: Caterpillar and Imago

Ruddy Daggerwing photos
Wed, May 13, 2009 at 2:55 PM
I have raised a few of these cats to butterflies for my children to see the entire process. I hope you enjoy the photos. I love your website.
Karen
Miami, Florida

Ruddy Daggerwing Caterpillars
Ruddy Daggerwing Caterpillars

Hi Karen,
Wonderful contributions like your metamorphosis images of a Ruddy Daggerwing, Marpesia petreus, help to make our website interesting.  The caterpillars of the Ruddy Daggerwing feed on the leaves of figs.

Ruddy Daggerwing

Letter 5 – Ruddy Daggerwing Caterpillar from Brazil

Subject: Catapiller
Location: Central Brazil
January 4, 2014 5:53 am
What is this guy? We found him in our garage and have not seen this type before.
Signature: Bug Boys

Ruddy Daggerwing Caterpillar
Ruddy Daggerwing Caterpillar

Dear Bug Boys,
We had this pegged as the caterpillar of a butterfly in the family Nymphalidae, and when we searched for possible matches, we learned it is a Ruddy Daggerwing Caterpillar because of a matching photo on Butterfly Fun Facts

We verified that identification on BugGuide, and according to the information page on BugGuide:  “Larvae feed on fig, Ficus species. In Florida this is likely to be Strangler Fig, Ficus aurea.”  We are deducing that you must have a nearby Ficus plant.  Butterflies of America, which pictures the adult Ruddy Daggerwing, confirms that this species is found in Brazil.

Wow, thanks! You are right.  We do have some Ficus around.  You are my boys new favorite website.
Sincerely,
Bridget

You are very welcome Bridget.  Though we have a significant number of Brazilian species on our site, most of our archives is made up of North American and Australian insects.  You might also want to look at Cesar Crash’s Insetologia website which is patterned on our format.  Cesar is a frequent contributor to What’s That Bug? and his site will most likely have more local species for you.

Letter 6 – Smeared Dagger Moth Caterpillar

Smeared Dagger Moth Caterpillar
Fellow bug fans,
My kids and I have used your site to identify dozens of insects over the past few years. Your site is always the first place we go when our paper guidebooks fail us. Once again you’ve come through for us in identifying what we believe to be a Smeared Dagger Moth caterpillar (Acronicta Oblinita).

We found this one feeding on marsh grass along the shore of Jug Bay on the Patuxent River in Maryland. You have a couple pictures of them, but we thought you might like another. Thanks for a wonderful website!
Ned

Hi Ned,
We love hearing from people who have the patience to plow through our archives and successfully identify their unknown invertebrate discoveries. Your identification of the Smeared Dagger Moth, Acronicta oblinita, is on the money.

Letter 7 – Smeared Dagger Moth Caterpillar

Subject: eating lotus leaf
Location: delaware
September 17, 2014 1:48 pm
found him a couple days ago. never saw anything like it
Signature: curious bug

Smeared Dagger Moth Caterpillar
Smeared Dagger Moth Caterpillar

Dear Curious Bug,
This is a Smeared Dagger Moth Caterpillar,
Acronicta oblinita, also known as a Smartweed Caterpillar.  Interestingly, we located another image online on All Posters that is feeding on a lotus leaf.  According to BugGuide, the caterpillar feeds on “A variety of forbs, shrubs, and trees” and “Caution, larva may ‘sting’ if handled.”

Letter 8 – Smeared Dagger Moth Caterpillar

Subject: large caterpillar, white/yellow body with red hair tufts
Location: Missouri, United States
June 1, 2015 6:26 pm
so despite my best efforts to identify this lil fella, I have not found anything coming close so I turn to this website which has helped me identify many things and taught me so much.
it was found on what seems to me like some sort of tall grass-type plant.
I’m keeping a log of all the sorts of caterpillars I find this year and would love to know the name of this one to write it down.
Signature: Stolz

Smeared Dagger Moth Caterpillar
Smeared Dagger Moth Caterpillar

Dear Stolz,
Your caterpillar is that of a Smeared Dagger Moth,
Acronicta oblinita, and you can compare your individual to this image on BugGuide.  According to BugGuide:  “Caution, larva may ‘sting’ if handled.”

Letter 9 – Smeared Dagger Moth Caterpillar

Mystery caterpillar
Dear Bugman,
I’m hoping you can identify this caterpillar. We found it in our native plant nursery outside of Annapolis, MD and the closest picture I can find that looks like it is the Western Tussock Moth. Is there an eastern version, or is this one a vacationer here on the Chesapeake Bay? Or is this a totally different moth/butterfly?

We have found many different caterpillars and have been able to figure out the parents of most of them, but this one has us stumped. (The farmer who leases the land to us is amazed that we are growing “weeds” but delighted by the butterflies.)

Any help you give us would be greatly appreciated…we like to be able to tell children what the “bugs” are when they find them on the plants. The plant the caterpillar is sitting on is a Shining Sumac, Rhus copallina. Thanks….your website is amazing!
Ann

Hi Ann,
Thank you for getting back to us with the host plant, shining sumac. We were not going to give up until we identified your caterpillar because we love your letter. Long live the native weeds and thank you for sharing such a wonderful viewpoint with your children. We finally located your caterpillar on BugGuide. It is a Smeared Dagger Moth Caterpillar, Acronicta oblinita.

Caterpillars of the Eastern Forests notes: “Pattern highly variable but always handsomely marked: generally dark, with dark or reddish dorsal warts bearing tuft of short bristly setae. Head black, shiny. Dorsum with or without abundant white speckling. Yellow, inverted V-shaped blotches separate white spiracles. Four fine setae extend out from others at either end of body. Food: many forbs, shrubs, and trees.”

Letter 10 – Smeared Dagger Moth Caterpillar on Milkweed

Subject: What is this caterpillar
Location: east central Indiana
August 22, 2013 4:08 am
My son found this caterpillar munching milkweed in Indiana and we haven’t been able to ID it. Can you help please?
Signature: Karen

Unknown Caterpillar on Milkweed
Unknown Caterpillar on Milkweed

Dear Karen,
Your caterpillar’s identity is eluding us, though we did find what looks like the same caterpillar unidentified on Michael Powell’s Blog which has numerous nice caterpillar photos. 

Mr. Powell states:  “I came across this colorful specimen while on a nature walk at a local marsh. He was close enough to the edge of the path that I was able to set up my tripod and shoot with my macro lens, so I was able to get a reasonable depth of field.  I don’t have the slightest idea what kind of a caterpillar this is, but I really like his colors and all of the hairy, spiny things sticking out of his body (even if they made focusing a bit of a challenge).” 

We then searched our own archives and we found a Smeared Dagger Moth Caterpillar, Acronicta oblinita, which looks like a good match, but we were not aware they fed on milkweed.  According to BugGuide, it feeds on:  “A variety of forbs, shrubs, and trees.”  It is also called a Smartweed Caterpillar.

Letter 11 – Smeared Dagger Moth: Was Unidentified Willow Eating Caterpillar in Florida

Unidentified caterpillar
Hello. I’m so glad to have found your website, as my coworkers and I constantly come across critters while doing natural areas restoration work for the County here in South Florida. I recently came across this caterpillar feeding on willow in a freshwater wetland. Any ideas on its identity?
Jane Griffin Dozier
Environmental Resource Project Supervisor
Miami-Dade County Park & Recreation
Natural Areas Management
Miami, FL

Hi Jane,
We don’t recognize your caterpillar. While we continue to research what it might be, we will post your photo and perhaps someone will recognize it.

Update (04/25/2006)
Hi there. I thought I’d give you an update on this caterpillar. Thanks to a Naturalist here with the Parks Department, it has been positively identified as a smeared dagger moth (Acronicta oblinita). Thanks.
Jane

Letter 12 – Ruddy Daggerwing Caterpillar from Santa Lucia

bright orangy/red/yellow, black blue spots/stripes and blue spikes!
Location:  Saint Lucia (near the Vieux Fort light house)
October 9, 2010 6:58 pm
Hello!
So, I spent the past few hours scanning through your site looking for this guy! I haven’t found anything yet!
I was hiking the roadway up in Saint Lucia in May 2010 when this guy was spotted. Any ideas??
Thanks for having such a great site!
Signature:  Joe

Ruddy Daggerwing Caterpillar

Dear Joe,
We do not recognize your Caribbean Caterpillar.  We will try to research this species and we would also request assistance from our readership.

Thanks!
I’ve attached a ‘top view’ as well.
Perhaps that will help??
I’m not sure what else I could tell you that would help…
Joe

Ruddy Daggerwing Caterpillar

Young Ruddy Daggerwing
October 11, 2010
You’re slippin’, Daniel . . .
2010/10/10/unknown-caterpillar-from-santa-lucia/
. . . is an easy one: caterpillar of the Ruddy Daggerwing (Marpesia petreus).
Best wishes,
Keith 🙂

Thanks for the assistance Keith,
Daniel purposely leaves a few unidentified species so that the website will be truly interactive.  Has he saved face?  Actually, he knew that this was a species previously identified, but it was not one of the Heliconias he quickly scanned on BugGuide prior to posting.  The Ruddy Daggerwing can also be found on BugGuide.

Hi Daniel and Joe:
This handsome caterpillar is a Ruddy Daggerwing, Marpesia petreus (Nymphalidae). It ranges from the southern USA to South America, including the West Indies where it is also called the Tailed Flambeau (I like that). Here is another look. Regards. Karl

Thanks Karl,
We also like the name Tailed Flambeau.  We actually think that common name could apply to either the caterpillar or the imago and the colors of the caterpillar really do resemble the colors of a burning torch.

Letter 13 – Unknown Florida Caterpillar is Ruddy Daggerwing

ficus creature
Heya guys, Cool site. I live in South Florida and I found this tasty little morsel under a ficus tree after a July rain storm. I don’t know if it crawled there or fell from the tree. Any way I hope it wasn’t poisonous! So what was it? seeya,
Britt

Hi Britt,
We do not recognize your caterpillar, but have decided to post it before trying to identify it. Structually, it resembles a Milkweed Butterfly in the subfamily Danainae, but not the species represented on BugGuide found in Florida. The coloration is quite different. It also doesn’t matche the species found on Geocities from Australia. We wonder if perhaps this is some tropical species that found its way to Florida, or if it is an escapee from a butterfly pavilion.

Update: (07/15/2008)
Daniel:
Had we not had one of these caterpillars posted on Bugguide about a week ago, I never would have known what it was, either. But, it is the larva of the “ruddy daggerwing” butterfly, native to Florida. Neat find, great pic!
Eric

Thanks Eric for the information about the Ruddy Daggerwing, Marpesia petreus.

Authors

    by
  • Bugman

    Bugman aka Daniel Marlos has been identifying bugs since 1999. whatsthatbug.com is his passion project and it has helped millions of readers identify the bug that has been bugging them for over two decades. You can reach out to him through our Contact Page.

  • Piyushi Dhir

    Piyushi is a nature lover, blogger and traveler at heart. She lives in beautiful Canada with her family. Piyushi is an animal lover and loves to write about all creatures.

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