Question Mark Caterpillar: Essential Guide for Curious Minds

The question mark caterpillar is an intriguing insect with striking features that many may not be familiar with. As the larval stage of the question mark butterfly, these caterpillars are not only fascinating to observe, but they also play a role in the life cycle of these beautiful butterflies.

Growing up to 1 1/2 inches long, question mark caterpillars have a reddish-brown head and a body covered in short spines, irregular pale lines, and speckles, giving them a distinct spiny appearance source. Over the course of 3 to 4 weeks, they transform from their larval state into the stunning question mark butterflies, serving as an essential part in North Carolina’s diverse ecosystem, which is home to nearly 3,000 species of caterpillars source.

Question Mark Caterpillar Overview

Polygonia Interrogationis

Question Mark Caterpillar is the larval stage of the Question Mark Butterfly, scientifically named Polygonia interrogationis. These caterpillars are mainly found in North America, spanning across the United States and Canada.

Physical Characteristics

The Question Mark Caterpillar has the following features:

• Reddish-brown head with short spines
• Dark body with irregular pale lines and speckles
• Spiny protuberances on each segment

These caterpillars start small and gradually grow, reaching a length of about 1 1/2 inches. In their 3-4 weeks of larval stage, they undergo transformations that grant them a distinctly spiny appearance.

Related Species

The Question Mark Caterpillar is related to the following species:

• Eastern Comma (Polygonia comma)
• Green Comma (Polygonia faunus)
• Compton Tortoiseshell (Nymphalis l-album)

These kin species share similar features and habitats, yet differ in colors, markings, and/or tails.

Life Cycle and Habitat

Caterpillar Stage

• The Question Mark caterpillar is spiny with a reddish-brown to black color.
• It feeds on various plants like nettles, elms, and hackberries.

Butterfly Stage

• Adult Question Mark butterflies have a wingspan of 2.5 to 3 inches.
• Their wings are orange with black spots, and a silver “question mark” shape on the hindwing.

Host Plants

• Host plants include nettles, elms, and hackberries.
• Caterpillars feed on leaves, while adults consume nectar, rotting fruit, and tree sap.

Preferred Environment

• Question Mark butterflies prefer wooded areas, open spaces, and woodlands.
• They are commonly found along forest edges, urban parks, and gardens.

Comparison Table:

Feeding Preferences and Behavior

Favorite Host Plants

The Question Mark caterpillar has some favorite host plants to feed on, which include:

• Elm trees (American Elm and Red Elm)
• Hackberry trees
• Nettles
• False nettles
• Japanese hops

These native plants are commonly found in Wisconsin and other parts of the United States.

Adult Butterfly Diet

Adult Question Mark butterflies have a different diet compared to their caterpillar stage, consisting of:

• Nectar from various flowers
• Tree sap
• Decaying fruit

Below is a comparison table of the diets between the caterpillar and adult butterfly stages:

In summary, Question Mark caterpillars feed on a variety of native plants like elm, hackberry, nettles, and false nettles. As adult butterflies, they consume nectar, tree sap, and decaying fruit. Understanding the feeding preferences and behavior helps us better appreciate and conserve these fascinating creatures.

Physical Adaptations and Defense Mechanisms

Spines and Venom

• Question mark caterpillars have spines that serve as a primary defense mechanism.
• These spines are venomous, providing protection against predators.

A notable physical adaptation of the question mark caterpillar is its spines. The caterpillar’s spines serve a crucial role in its defense against potential threats. These spines contain a venom, which can deter predators from attempting to consume the caterpillar.

Coloration and Camouflage

• Coloration of the caterpillar helps in its camouflage.
• Silver spots on the caterpillar’s underside resemble a leaf for further disguise.

In addition to spines and venom, question mark caterpillars employ coloration and camouflage to protect themselves. Their body color is such that it allows them to blend in well with their surroundings. One striking feature of these caterpillars is the presence of silver spots on their underside, making them appear as a leaf, which further enhances their camouflaging ability.

In summary, the primary physical adaptations and defense mechanisms of the question mark caterpillar are its spines, venom, and camouflage-enhancing coloration. These features help the caterpillar to avoid predation and increase its chances of survival.

Attracting Question Mark Caterpillars to Your Backyard

Host Plants to Grow

To attract question mark caterpillars to your backyard, it’s essential to provide them with their preferred host plants. Some examples of host plants include:

• Elms (Ulmus spp.)
• Hackberry (Celtis spp.)
• Nettles (Urtica spp.)
• False nettles (Boehmeria spp.)

These plants not only provide food for caterpillars, but they also serve as a perfect location for female butterflies to lay their eggs.

Providing Food and Shelter

When transforming your backyard to a question mark caterpillar haven, consider providing:

• Rotting fruit: Question mark butterflies are attracted to rotting fruit, as they provide a rich source of nutrients.
• Nectar sources: Plant flowering plants that produce nectar for butterflies to feed on. Some examples include milkweed, aster, and goldenrod.
• Carrion: Although it might not be ideal for some, question mark butterflies are also attracted to carrion, which provides essential nutrients for their survival.
• Parks and nature reserves: Having a backyard near parks or nature reserves can also increase the chances of attracting question mark caterpillars.

By implementing these changes, you can create a welcoming environment for question mark caterpillars and enjoy the beauty of these fascinating creatures in your backyard.

Further Resources and Information

Guides and Books

• For a comprehensive guide on caterpillars, including the Question Mark Caterpillar, you can consider purchasing a book on Nymphalidae family, which covers their characteristics and features, such as their distinct hind wing shapes and patterns.
• Field guides about insects of North America are another excellent resource for identifying and learning about these fascinating creatures.

Websites and Online Communities

• Websites such as BugGuide provide detailed information on various insects, including the Question Mark Caterpillar.
• You can also participate in online communities, like forums or Facebook groups, dedicated to insect enthusiasts who share their knowledge, experiences, and images of insects like the Eastern Comma and Question Mark Caterpillar.

• Some prominent characteristics of Question Mark Caterpillar include:
  • Bright coloring with multiple shades (yellow, green, brown)
  • Multiple legs with a spiky and bristly appearance
  • Unique question mark-shaped silver mark on the hind wing

Keep in mind that while studying the Question Mark Caterpillar, it’s important to respect and appreciate the intricate nature of these insects without causing harm to them or their environment. Happy exploring!

Reader Emails

Over the years, our website, whatsthatbug.com has received hundreds of letters and some interesting images asking us about these insects. Scroll down to have a look at some of them.

Letter 1 – Questionmark: Black Form

Eastern Comma in Southern Ontario?
Good day,
I took a picture of this butterfly while on a lengthy bike ride in southern Ontario, Canada. I was on the ‘Rail Trail’ between Brantford and Hamilton Ontario, a path that was once used by trains, now a trail used for public leisure. From what I’ve seen and read, I believe it may be an Eastern Comma. The problem is that the pattern and colouring on the rear wings doesn’t match those I’ve seen on that particular species. I’ve attached the image file to this email. Feel free to use it on your site if you decide to respond. Thanks for your time,
Terry Howes

Hi Terry,
We first opened your email yesterday, but were unable to post at the time. Trying to sort through all of our incoming mail to relocate your letter was no small undertaking. This is a Questionmark, Polygonia interrogationis, the black form. The Questionmark is the only Anglewing with, according to Jeffrey Glassberg, “a small black horizontal bar on the subapical FW above.” The black form, with the dark hind wings is the summer form.

Letter 2 – Questionmark Caterpillar

Subject: Caterpillar found while weeding
Location: Austin, Texas
June 24, 2012 1:28 pm
Hi!
I found three of these beautiful caterpillars while pulling weeds today. Unfortunately, I injured one before seeing them, but did manage to not harm the remaining two. They are eating on an unknown weed to me.
I have used your website in the past to identify many bugs, but after searching for 2 hours, I still have been unable to identify this caterpillar. I am hoping you can help me.
Signature: Deborah

Hi Deborah,
We believe this is a Questionmark Caterpillar, and that is an actual species identification and not a confused reply.  We matched your photo to an image of a Questionmark Caterpillar, Polygonia interrogationis, that we located on BugGuide.  According to BugGuide:  “Caterpillars feed on nettle, false nettle, elms, hackberry, Japanese hops.”  We only have one previous posting of a Questionmark Caterpillar, so it was easy to overlook while scanning our site.  We do have numerous images of the adult Questionmark which gets it common name from a silver mark on the underside of the hind wings which is thought to resemble the interrogation mark.

Thank you so much! I had assumed it was a moth caterpillar since we see many more moths than butterflies here in Austin. I still cannot figure out what they are feeding on, even after looking up pictures of the plants mentioned in BugGuide. I sure hope to see more of these!
Deborah

The food plant list might be incomplete.

Letter 3 – Questionmark Caterpillar

Subject: Questionmark caterpillar photos for you
Location: Central MN
June 25, 2012 7:50 am
I see you have only one questionmark caterpillar photo. Here are a couple more.
Unfortunately, a tachinid fly parasitized this caterpillar, so no chrysalyis shots.
Darn it.
Signature: Don J

Hi Don,
Thank you for sending us some additional photos of a Questionmark Caterpillar.  They are greatly appreciated and a fine addition to our archives.  It appears there is netting in one of your photos.  Do you raise caterpillars in captivity?  Do you have a photo of the Tachinid that emerged?

Hi Daniel.
I’m glad you liked the photos.  This caterpillar was on a hackberry tree in our yard, but yes, I did photograph her(?) on netting.  The tachinid that emerged was still in larval form (as was another that came out of a monarch chrysalis at the same time.  The little maggots mad me angry, so I threw them in the woods!  They’re lucky I didn’t just smash them, or use them for fish bait (that thought occured to me too late).
Anyhow, yes, I do raise caterpillars – mostly monarchs, but others when I come across them.  I especially like cecropia and polyphemous moths, but don’t have any yet this season.
Cheers.

Letter 4 – Questionmark Caterpillar

Subject: Spiky caterpillar,
Location: central MO, USA
April 28, 2014 7:03 pm
I took a picture of this caterpillar in early September 2006, he was on my tomato plants… I plucked the leaf he was on and put it on a chair so I could try to figure out what he was… never did find out. Here’s the picture, It looks similar to the Mourning Cloak Caterpillar which is on here, but different enough that I think it is a different caterpillar, maybe the spiny elm caterpillar?
Signature: jaelle62

Dear jaelle62,
You actually got quite close with your identification attempt.  We believe this is the caterpillar of a Questionmark, Polygonia interrogationis, a butterfly in the same tribe as the Mourning Cloak, Nymphalini.  You can compare your image to this image from Bugguide.  Are you growing hops in your garden?  According to BugGuide, the “Caterpillars feed on nettle, false nettle, elms, hackberry, Japanese hops.”

Letter 5 – Questionmark Caterpillar

Subject:  Caterpillar
Geographic location of the bug:  Fieldale, VA
Date: 06/08/2019
Time: 08:38 PM EDT
Your letter to the bugman:  Can you please help me identify this caterpillar I pulled off my hops plant in late May/early June?
How you want your letter signed:  Sandra Nester in VA

Dear Sandra,
When attempting to identify plant feeding insects, it is tremendously helpful to know the food plant.  Thanks for informing us this Caterpillar was feeding on hops.  We quickly identified it as the caterpillar of a Questionmark butterfly thanks to BugGuide.  Here is a BugGuide image that looks even more like your individual.  The adult Questionmark is a beautiful butterfly.

Letter 6 – Questionmark Caterpillar

Subject:  Caterpillar
Geographic location of the bug:  CT
Date: 06/30/2019
Time: 05:41 PM EDT
Your letter to the bugman:  Dear Bugman,
I’ve been unable to find this one in my Caterpillars of Eastern North America book, or online.  It was photographed on lam’s quarters, but I don’t know if it was feeding.
How you want your letter signed:  Thanks for taking pity on my curiosity!

Dear Tftpomc,
Though the colors seem light by comparison, we believe your caterpillar is that of a Questionmark butterfly, Polygonia interrogationis, similar to this BugGuide image.

Letter 7 – Questionmark Caterpillar

Subject:  Caterpillar identification
Geographic location of the bug:  Columbus OH, central
Date: 07/19/2019
Time: 12:30 PM EDT
Your letter to the bugman:  Found this guy while landscaping, was on the ground in some clover weeds. July 18th 2019, 93 degree weather
How you want your letter signed:  Anthony C

Dear Anthony,
This is the caterpillar of a Brush Footed Butterfly in the family Nymphalidae.  Based on this and other BugGuide images, we are pretty confident this is a Questionmark Caterpillar.

Letter 8 – Questionmark Emerges, Fascinates Toddler!!!

Subject: Our blooming Bugthusiest
Location: South West Manitoba, Canada
July 17, 2012 8:54 pm
Hi there! Just wanted to submit a couple of photos of my 21month old son’s first ”bug” catch & release. We had tons of these greenish brown caterpillars covered in little spikey things in our elm trees. So we captured three but could not pinpoint what they would become. One ended up cocooning in our bug box, so we kept them around to see what they would turn into. We found out today when the first on emerged! I believe they are comma butterflys. Unfortunately, we were in town when it happened, but hopefully I can get a picture of the other two emerging, that would be neat! Gorgeous little thing though, I was thinking it would just end up being a muddy brown moth or a pest or something hah hah! Nice surprise when we got home though! 🙂 Thanks for having such a great site btw!
Signature: Angela & Zach

Dear Angela and Zach,
In addition to having a gorgeous photograph of a newly eclosed Questionmark (the other punctuation species), your entry has that elusive human interest angle.  If you want to perpetuate Questionmarks in your yard, you should continue to cultivate the plant upon which you found the caterpillars.  According to BugGuide:  “Adults take fluids from soil, rotting fruit, feces, carrion. Seldom, if ever, take nectar. Caterpillars feed on nettle, false nettle, elms, hackberry, Japanese hops.”  In general, providing habitat for caterpillars is the critical component to having butterflies (and Moths).  Adult butterflies are attracted to caterpillar habitat so that they can lay eggs.  Newly emerged butterflies will also be found near the larval food source.  Adult butterflies tend to remain where there is a caterpillar host plant, but they will also need to stray to good nectar areas as well as “rotting fruit, feces, carrion” in the case of your Questionmark according to BugGuide.

The photos of your Bugthusiast are very cute.  We hope you are lucky enough to witness the eclosion stage of the metamorphosis process, undeniably the most dramatic moment of the Complete Metamorphosis cycle.

Letter 9 – Questionmark most likely

Subject: Butterfly or Moth? Then what kind?
Location: New York
July 18, 2014 7:30 am
I live in Upstate New York and found this guy fluttering around. I’m sure it’s common but cannot find one with the same ratio of orange on top wings to basically all brown lower wings.
Signature: Thank You, Sarah Burr

Dear Sarah,
This is one of the Anglewing Butterflies in the genus Polygonia.  We believe it is the Questionmark, Polygonia interrogationis.  These are butterflies that hibernate, and judging from the tattered wings, this is an old individual, perhaps one that originally emerged in Fall 2013 and hibernated through the winter.  It is likely near the end of its life.  Here is a BugGuide image of a lovely younger individual.  The common name Questionmark is due to the presence of a silver marking on the ventral surface of the hindwing which resembles the punctuation mark.

Letter 10 – Questionmark: Winter Form

Question Mark Butterfly (Polygonia interrogationis)
Location: Naperville, IL
September 25, 2011 11:07 pm
Hi Daniel~
I think this is a winter form question mark butterfly (as opposed to a summer form). I read that they rarely take nectar, but this one couldn’t seem to get enough of this pink delight buddleia. It flew from flower to flower and hung around for nearly 30 minutes while I snapped away.
All the best,
Signature: Dori Eldridge

Hi Dori,
Your photos are really quite lovely.  The closed wing view nicely showcases the silvery questionmark on the hind wings.  We agree that this is the fall or winter color form of an individual that will most likely pass the winter in hibernation.  According to BugGuide:  “Adult: underside of hindwing has unique silver “question mark” shape. Upper forewing has extra black dash not in the similar Eastern Comma. (2) Upper hindwing of summer form is mostly black with short tails; winter form is orange/black with longer violet tipped tails. (1) Wing are very angular in outline.”  Here is a photo from BugGuideof the darker summer form for comparison.

Letter 11 – Which Anglewing is it????

Subject: Butterfly and, i think, moth
Location: Edmonton,AB Canada
September 14, 2013 8:08 pm
Hi, i`ve spotted this two beauties in my garden. Butterfly in end of August, and second large Butterfly or maybe it`s a moth beginning of June. I live in Edmonton Alberta, Canada. I love everything about garden and what`s flying around it .
I`m sending one pic. of butterfly and 2 pics of Butt./moth. which was about 6-7cm by 10-11cm in size.
Please let me know what are those . I`m not in a rush to hear the answer, but whenever you have time.
Thanks alot
Oxana
Signature: Oxana

Hi Oxana,
Your butterfly is one of the Anglewings in the genus Polygonia, but we cannot say for certain which species.  We suspect it is the Eastern Comma, Polygonia comma, but we are not certain.  Perhaps one of our readers can make a more definitive identification.  See BugGuide for more information on the Anglewings.  Your moth is a Polyphemus Moth.