Isabella Tiger Moth: All You Need to Know in a Nutshell

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The Isabella Tiger Moth is a fascinating insect that has captured the interests of many nature enthusiasts. This beautiful, medium-sized type of tiger moth, known scientifically as Pyrrharctia isabella, is most recognizable for its distinct appearance. With their forewings being yellow or tan, pointed, and often having faint lines and small dark spots, these moths rest with their wings held roof-like over their bodies or flat out to the sides. In addition, their hindwings are lighter and appear orange in females, while the bases of their forelegs showcase a reddish-orange color 1.

Perhaps even more famous than the adult moth is its larval stage, commonly called the “woolly bear” or “woolly worm.” These fuzzy, spine-covered caterpillars grow up to 2.25 inches in length and feature red-brown coloring with black ends 2. The woolly bear is known for its association with weather folklore – they’re said to predict the severity of the upcoming winter based on the size of their black bands. Whether or not this is true, the Isabella Tiger Moth remains an intriguing subject of study for moth enthusiasts and casual observers alike.

Isabella Tiger Moth: Basic Information

Scientific Classification

The Isabella Tiger Moth belongs to the following classification:

  • Kingdom: Animalia
  • Phylum: Arthropoda
  • Class: Insecta
  • Order: Lepidoptera
  • Family: Erebidae
  • Subfamily: Arctiinae
  • Genus: Pyrrharctia
  • Species: Pyrrharctia isabella

Common Names

  • Isabella Tiger Moth
  • Woolly Bear
  • Woolly Worm

The Isabella Tiger Moth (Pyrrharctia isabella) is a species of moth from the family of Erebidae and the subfamily Arctiinae. Known for its distinctive coloring, adult Isabella Tiger Moths have forewings that are yellow or tan with faint lines and small dark spots. Hindwings are lighter and orange in females.

This moth’s larvae are commonly referred to as woolly bears or woolly worms. These are particularly famous as weather predictors, although with no scientific accuracy. The distinct hairs called setae and the color bands displayed on the body are characteristics shared by all woolly bears.

Some key features of the Isabella Tiger Moth include:

  • Medium-sized moth with a wingspan of about 2 inches
  • Distinct orange-brown forewings
  • Lighter hindwings (orange in females)
  • Reddish-orange bases of forelegs

In summary, the Isabella Tiger Moth is an interesting and easily identifiable moth that belongs to the Erebidae family.

Physical Characteristics


The adult Isabella tiger moths are medium-sized, with a wingspan ranging from 22 to 26 mm. Their forewings are typically yellow or tan, often featuring faint lines and small black spots. In contrast, the hindwings are lighter, with females exhibiting a more orange hue.


Larvae of this species, known as woolly bears or woolly worms, are quite fuzzy with dense, stiff hairs. They display black ends on their bodies and a rusty red or brownish middle section. When disturbed, these caterpillars typically curl up into a ball.

Differences between adults and larvae:

Feature Adults Larvae
Size 22 – 26 mm wingspan Smaller than adults
Color Yellow/tan, orange Black, rusty red
Body Hairs None Dense, stiff hairs
  • Sexual dimorphism: Female Isabella tiger moths have more orange hindwings compared to males.
  • Note: Touching the larvae’s bristles may cause dermatitis in some people.

Life Cycle and Reproduction


  • Oval-shaped
  • Yellowish-white color

The Isabella tiger moth (Pyrrharctia isabella) begins its life as an egg. Female moths lay oval-shaped, yellowish-white eggs on plants, where they remain until hatching.


  • Distinct black and chestnut color bands
  • Commonly known as “woolly bears”

When the eggs hatch, they release larvae with distinct black and chestnut color bands, commonly known as “woolly bears.” These caterpillars feed on various plants and grow through several stages (instars) before entering the pupal stage.


  • Cocoon made of silk and hairs from its body

The larva eventually forms a cocoon, made primarily of its own silk and incorporating hairs from its body. Inside this protective structure, it transforms into a pupa, undergoing metamorphosis to become an adult moth.

Adult Moth


  • Forewings: yellow or tan with faint lines and small dark spots
  • Hindwings: lighter, orange in females
  • Reddish-orange foreleg bases

The adult Isabella tiger moth emerges with yellow or tan forewings, often featuring faint lines and small dark spots. The hindwings are lighter, with an orange hue in females. One defining characteristic is the reddish-orange base of the forelegs. Adult moths feed on nectar and are also pollinators, playing an important role in the ecosystem.

Diet and Feeding Habits

The Isabella tiger moth is known for its distinct larval stage, commonly called the “woolly bear.” During this stage, the larvae feed on a wide variety of host plants.

Some key features of their diet include:

  • Host plants: A diverse selection, including trees, flowers, grasses, and other vegetation.
  • Feeding habits: Herbivorous, consuming plant matter for sustenance.
  • Larval stage: The primary time for feeding and growth.

Here is a brief comparison of the Isabella tiger moth’s diet to other moths’ diets:

Moth Species Host Plants Feeding Habits
Isabella Tiger Moth Trees, flowers, grasses, etc. Herbivorous, consume plants
Other Moths Specific host plants May consume plants, nectar, etc

While the Isabella tiger moth feeds primarily during its larval stage, adult moths consume nectar from various flowers to sustain energy.

In summary:

  • Isabella tiger moth larvae have a diverse diet of host plants, including trees, flowers, grasses, and other vegetation.
  • They are herbivores that primarily feed during their larval stage, also known as the “woolly bear” stage.
  • In their adult form, they consume nectar from flowers for sustenance.

Habitat and Distribution

The Isabella tiger moth, scientifically known as Pyrrharctia isabella, is found in a wide range in North America. Its distribution stretches across the United States, Canada, and Mexico.

  • United States: from Florida to Alaska.
  • Canada: in territories such as Yukon, Northwest Territories, and Newfoundland.
  • Mexico: mainly in northern regions close to the US border.

These moths are quite adaptable and can be found in various habitats, like:

  • forests
  • meadows
  • residential areas with gardens and parks

Isabella tiger moths are known for their colorful caterpillar stage called the woolly bear. They are a well-known species and are often studied for their ability to survive in freezing temperatures.

An interesting fact about the Isabella tiger moth is their relationship with bats. Bats are a natural predator of moths, but the Isabella tiger moth has developed an evasive mechanism. They emit ultrasonic clicks to ward off bats and increase their chance of survival.

Isabella Tiger Moth Other Moths
Range North America varies
Habitat forests, meadows, residential areas varies
Distribution United States, Canada, Mexico varies
Predators bats varies

In summary, the Isabella tiger moth is a unique species found predominantly in North America. They can adapt to various habitats and have developed a defense mechanism against their natural predators, such as bats.

Banded Woolly Bear and Woolly Worm


The banded woolly bear, also known as the woolly worm, is believed to predict the harshness of the upcoming winter weather. Folklore states that the wider the black bands on the caterpillar, the harsher the winter will be. These creatures are found in various regions, including the state of Missouri.

Woolly Worm Festival

Every year, a festival called the Woollybear Festival takes place to celebrate this fascinating creature. The event features activities related to the banded woolly bear caterpillar.

  • Caterpillar features:

    • Fuzzy with dense, stiff hairs.
    • Usually black on the ends and rusty red or brownish in the middle.
    • Rolls up in a ball when disturbed.
  • Caterpillar characteristics:

    • Larva of the Isabella tiger moth.
    • Hibernates during winter.
    • Bristles may cause dermatitis in some people.

Comparing the banded woolly bear with other insects may be interesting to some readers:

Feature Banded Woolly Bear (Woolly Worm) Other Common Insects
Predicts weather Yes, through its bands’ widths No
Furry appearance Yes No
Hibernates Yes Some species
Causes dermatitis In some people Some species

In summary, the banded woolly bear caterpillar has a significant role in folklore and cultural events. Its unique features and characteristics differentiate it from other insects.

Defense Mechanisms and Health Considerations

The Isabella tiger moth’s larvae, commonly known as the woolly bear or woolly worm, possess dense, stiff hairs. These hairs serve as a defense mechanism and protect the larvae from predators. On the downside, when humans touch the bristles, some people may experience an irritating rash or dermatitis. This reaction is different from a sting, but it is still unpleasant. Hence, caution is advised when handling woolly bears.

Parasitic relationships exist in the insect world. For instance, woolly bear caterpillars can be parasitized by wasps. The wasps lay their eggs inside the caterpillar, and the developing larvae live off the woolly bear’s body. Eventually, they emerge and spin a cocoon near the remains of the woolly bear.

To summarize the defense mechanisms and health considerations:

  • Woolly bear caterpillars have dense, stiff hairs as a defense mechanism against predators
  • Touching the bristles can cause irritation, rashes, or dermatitis in some people
  • Parasitized by wasps, which lay eggs inside the caterpillar’s body

Comparing the effects of touching a woolly bear caterpillar versus a stinging insect:

Woolly Bear Caterpillar Stinging Insect
Causes rash or irritation Yes No
Causes a sting No Yes
May cause allergic reaction No Yes

Connections to Pop Culture, Travel, Literature, and Science


The Isabella tiger moth has made appearances in literature, notably in Sir James Edward Smith’s work titled “The Natural History of the Rarer Lepidopterous Insects of Georgia”. It showcases the moth’s fascinating anatomy and life cycle.


In scientific research, the Isabella tiger moth is studied for its unique characteristics:

  • Ability to survive freezing temperatures
  • Vivid color patterns

Scientists are particularly interested in this moth’s banded woolly bear larvae’s capacity to withstand harsh winter conditions.


Fans of nature and moth enthusiasts often enjoy:

  • Observing the Isabella tiger moth in its natural habitat
  • Photographing this vibrant insect for documentation or personal collections


Travel destinations for those interested in observing the Isabella tiger moth include:

  • North America, particularly in the Eastern United States
  • Northern Mexico
  • Southern Canada

Visiting these regions can offer a valuable opportunity to experience this captivating species up close and witness its remarkable survival skills in various environments.


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Reader Emails

Over the years, our website, 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 – Woolly Bear Hatchlings, we believe


Subject: Small bug size of rice on wall
Location: Austin, Texas near/on lake USA
January 20, 2013 9:11 pm
Found this one night when I came home on the wall. They were all together just hanging out. The size of a piece of rice each of them are. That’s about all I know. Email me if you have any questions or I can help.
Signature: Don’t need one

Possibly Woolly Bear Hatchlings

We believe these are newly hatched Tiger Moth Caterpillars, which are called Woolly Bears.  There are many North American Tiger Moths and we are not certain of the species.  Tiger Moths are frequently attracted to lights and females will lay eggs on wall.

Letter 2 – Unknown Woolly Bear from Colorado


Subject: Caterpillar identification.
Location: El Paso county colorado manitou spring 80829
January 27, 2016 11:26 am
I have posted this picture to many websites and know one can Identify it here is the information on it. I am in El Paso county colorado manitou spring at 8000 feet. I found it crawling on the rocks I do not know the host. It was August 16 2015.
Signature: Zack vogel

Woolly Bear
Woolly Bear

Dear Zack,
This is a Woolly Bear, the caterpillar of a Tiger Moth in the subfamily Arctiinae, but we are having a problem with its species identity.  We scoured BugGuide and we found an image of
Hypocrisias minima posted to BugGuide that is the closest match, but we are not satisfied that is a correct ID.  The Caterpillar of the Virginia Ctenucha pictured on BugGuide also looks similar, and it is reported from Colorado, but again, it does not look like an ideal match.  This Tiger Moth Caterpillar from Colorado posted to the Life of Your Time blog is also somewhat similar.  We are going to contact Julian Donahue, a Lepidopterist specializing in Arctiids in the hope he can provide some information.

Julian Donahue Responds
 The caterpillar may just be a color form of Pyrrharctia isabella, the “standard” woolly bear.
I suggest you contact the caterpillar guy, David Wagner at Univ. of Conn., who is publishing books on the subject.

David Wagner Responds
I am not sure I have seen it before and am very, very intrigued.
I am writing a book on caterpillars of western North America and I don’t think I have seen this one before.  It is possible it is the very rare Alexicles aspersa.  If not something in the genus Hypercompe.
Was the individual saved?  I would be quite interested in learning more about the elevation and location, and especially altitude of the capture.
Thanks for sharing.
David L. Wagner Professor
University of Connecticut

Thanks for the information Dave.
I run the pop culture website What’s That Bug? and the photo was sent to my site.
I will write back and request additional information and get back to you.
Daniel Marlos

Zack Responds
Unfortunately I did not save it because I did not want it to starve. I am around 7500 in Crystal park Manitou Springs Colorado In a mountain community. The mountain Is covered in pine, fer and blue spruce with large spots of Scrub Oak. It get up to the 90 degree weather in the summer time and get down to the 4 degrees and lower in the winter. Thank you if you need more in formation please let me know and can I have David Wagner email in case he whats to talk to me.

Letter 3 – Two Woolly Bears


is this 2 woolly bears
Location:  broadway va
September 9, 2010 1:07 pm
Hello, I have two little ones trying to find out if these two are in the woolly bear family if so could somone please tell me if you know.thanks
Signature:  critterlady

Woolly Bears

Dear critterlady,
Caterpillars of Tiger Moths in the family Arctiidae are often called Woolly Bears, and your two caterpillars appear to be Arctiids.  The more orange Woolly Bear might be a Salt Marsh Moth Caterpillar (see BugGuide) though they might both be caterpillars of the Virginian Tiger Moth,
Spilosoma virginica.  Though the caterpillars are variable in coloration, they are known as Yellow Woolly Bears.  BugGuide describes them as:  “Caterpillars very variable in color – beige/yellow/dark red-brown/black. Body covered in long soft hairs (setae) of variable length – some much longer than the others (more than three body segments in length). Often one long hair in center of each tuft. Spiracles white.

Letter 4 – Woolly Bear


Floridian Black Caterpillar.
Fri, Dec 12, 2008 at 2:41 PM
Hello Mr.Bugman, let me start by saying how very much I appreciate your work. I have a very limited knowledge of bugs, but this site has taught me much. I used to have a serious, very serious phobia of all bugs. But you have taught me to turn my fear into curiosity, and for that, I thank you.
I found this little guy out side my house, on the porch. We live in Northern Florida, in Milton, USA. This picture was taken in December, and the weather was about 20 degrees, and it had just rained. I was worried about this caterpillar, but because I feared I might harm him, I did not touch him. I checked and did not see this type of caterpillar on your site, so I do not know what species he is. Thank you for your time, it is very appreciated!
Much Love, Nick from Florida.
Nick L.
Milton, Florida, USA

Woolly Bear
Woolly Bear

Hi Nick,
Your caterpillar is a Woolly Bear, the caterpillar of a Tiger Moth.  We can’t be more specific than the subfamily Arctiidae.

Letter 5 – Woolly Bear


woolly bear caterpillar
Location:  Rancho Bernardo, CA
March 7, 2011
Good Evening!
I discovered hundreds of these caterpillars in a vacant lot near my house.  I have always known these cute little guys as woolly bears, but are there different types of woolly bears?  Also what is the specific moth they turn into?
Weather:  Rain in January then the first really warm weekend they were everywhere
Thank you so much for the information
C. Knapp

Woolly Bear

Dear C,
This is a caterpillar of a Tiger Moth in the subfamily Arctiinae.  They are commonly called Woolly Bears and there are many different species with similar caterpillars.  This might be the caterpillar of the Nevada Tiger Moth,
Grammia nevadensis, which is pictured on BugGuide.

Thank you for the quick reply.  Yes, this does look like the Nevada Tiger Moth caterpillar.  I have a few in a container so I will keep an eye on them.
Thanks again.  This site is wonderful!
C. Knapp

Letter 6 – Woolly Bear


Subject: Please identify this caterpillar 🙂
Location: Missouri, U.S.A.
April 1, 2016 5:35 pm
I was searching in my yard for any type of bug I could possibly find, so I picked up and old pipe, tipped it over and out rolled a black and orange fuzz ball! I was very exited by this, because I love caterpillars, which I am pretty sure this is. I think it is a pretty common type. Pretty please with cherry’s on top help me identify it!
Signature: Gracie S.

Woolly Bear
Woolly Bear

Dear Gracie,
This Woolly Bear is the caterpillar of the Isabella Tiger Moth.  According to BugGuide:  “The second brood overwinters as a caterpillar and pupates in Spring.”
  That means your caterpillar should make a cocoon very soon.

Dear Daniel,
Thank you very much for writing me back! I am looking very forward to seeing the cocoon. At first when I found the caterpillar I was very worried it was dead, because it wasn’t moving. It took a little while for it to do anything, but when it did I was very exited! Thanks again!

Letter 7 – Woolly Bear


Subject: What will this cool caterpillar be?
Location: Md
October 18, 2016 2:51 pm
How do you guy feel of this bug? Its size just like baby’s fingers. It moves very slow. Could you bug mans find out what it is?
Signature: BG

Woolly Bear
Woolly Bear

Dear BG,
This pretty Woolly Bear will become an Isabella Tiger Moth.

Letter 8 – Woolly Bear Caterpillar


Subject: What is this?
Location: Torrance, California
July 5, 2017 3:10 pm
Hi, I stumbled across your site after trying to figure out what type of caterpillar this is. I think this is a wooly bear but it doesn’t look exact so maybe it’s in a younger stage ?? Please help, my son loves bugs so I’d like to know what it eats and this little guy almost got squashed by a car. I found him while taking a walk at work. It was on the concrete in the shade not moving at all. It was a warm day today too about 75 degrees out. I work in Torrance California.. He was about 3-4 feet away from the nearest shrub where there’s a big tree and grass so not sure if he maybe fell out of the tree or something. Hes moving around I put him in a container with some water sprinkled in it. Hope you can help, TIA.
Signature: Jen

Woolly Bear

Dear Jen,
This does look like the caterpillar of a Tiger Moth, and many are called Woolly Bears.  Many are general feeders, including the Caterpillar of the Painted Tiger Moth, a common Southern California species.

Thank you for responding. I’ll do my research on how to make a comfy home for him/her.

Many Woolly Bears spend time in a dormant stage when food is scarce.  According to BugGuide regarding the Painted Tiger Moth: “Adults fly June to October. In Arizona the larvae go into prepupal diapause during the dry season, from the end of the monsoons (September) until spring.”  In our Los Angeles offices, we tend to find active Woolly Bears earlier in the spring, and then they hibernate.  They do not form a cocoon until late summer.

Letter 9 – Woolly Bear Fanmail


No time for a photo.
Hi Daniel,
I took a 2-mile walk this morning.  Unfortunately, one of my neighbors had fired up one piece of his heavy machinery.  So instead of walking in the quiet woods in the foothills of the Great Smoky Mountians and breathing in the fresh morning, mountain air, no birds were singing and diesel permeated the air.
As the front-loader was headed toward me, I saw some movement on the old, dirt road: a wooly bear!  It was solid black (and heading north!).  I picked it up, even though I knew better, and set it up on the embankment, curled tightly, as high as I could reach.  No ill effects, I’m pleased to report.  There was no time to get a photograph; I, too, had to get out of the way.
This wooly bear was solid black, so I’m not sure if it was a young Isabella Tiger Moth caterpillar or a Giant Leopard Moth caterpillar.
Thanx for listening,
R.G. Marion
Cosby, TN
P.S. Your book finally arrived, and I’m thoroughly enjoying it.  Nice job!

Dear R.G.,
Thanks for letting us know that you are enjoying Daniel’s book.

Letter 10 – Woolly Bear Hatchlings


Subject: Some kind of larva?
Location: Lubbock, Texas.
May 9, 2015 6:19 pm
Shortly after sunset I found this cluster right about eye level on the brick entry way to my home.
Any idea what they are?
Signature: Dan

Woollybear Hatchlings
Woollyb  Bear Hatchlings

Dear Dan,
These are hatchling Woolly Bears, the common name for caterpillars of Tiger Moths in the subfamily Arctiinae.  We cannot state for certain which species you encountered, but good candidate is the Eyed Tiger Moth or Giant Leopard Moth,
Hypercompe scribonia, and when fully grown, the Giant Leopard Moth Caterpillars are about two inches long and dark in coloration.

Woollybear Hatchlings
Woolly Bear Hatchlings

Letter 11 – Woolly Bears


Subject: Caterpillar
Location: Granada hills
March 28, 2015 10:36 pm
Very fluffy, and about the length of my thumb ( 2 inches)
Signature: Any

Woolly Bears
Woolly Bears

Dear Any,
These are Woolly Bears, the caterpillars of Tiger Moths in the subfamily Arctiinae.  If Granada Hills is in California, the most likely candidates are Painted Tiger Moth Caterpillars,
Arachnis picta, which are pictured on the Victorian on the Move blog, but interestingly, not on BugGuide, except for newly hatched individuals.  Your individuals are getting ready to pupate based on the size you indicated.  We just encountered two in our own garden yesterday, and had we realized the dearth of images on the web, we would have pulled out the camera.


  • Bugman

    Bugman aka Daniel Marlos has been identifying bugs since 1999. 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.

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  • 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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Tags: Tiger Moths

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17 Comments. Leave new

  • That looks like the caterpillar of a Giant Leopard Moth- Ecpantheria scribonia. Usually you can see red rings around it when it is curled up, but that picture is dark so it is hard to tell for sure. I have a pic of an adult I can send, if there isn’t one on the site already. The adults are beautiful.

  • sooo cute but, is it true that some burn at the touch?

  • caterpillars22
    October 10, 2012 7:28 pm

    I currenly have both of those caterpillars

    the one towards the top of the picture definitly looks like the Salt Marsh/Acrea moth caterpillar

    but the yellow one is one that still has me puzzled but i’m thinking Yellow Bear

  • Janine Woodard
    May 22, 2013 1:02 pm

    I found one of these caterpillars, about ten days after having it it looked like it had made some kind of web around it, then it looked like it shed its fur. I had what seem to me like a rustish color shell, then that turned black. It still looks like there is some fur on it though, its been almost three weeks and nothing has happened yet and I am getting worried. Any advise.

  • One exactly like this one landed on me around my chest, I kind of panicked about it and still kinda am, I’ve read and googled a lot about it and learn that some are venomous, I only felt a tickle/something crawling and that’s it and nothing has appeared on me or the area it was on at all, should I be worried?

    • You would know by now if your encounter was with a stinging caterpillar. You are probably mistaking a harmless Woolly Bear with a stinging Asp, the caterpillar of a Flannel Moth.

  • Susan Hopkins
    March 29, 2015 2:04 pm

    What is the host plant for Woolly Bears?

    • There are many species of Woolly Bears. These Painted Tiger Moth Caterpillars are not limited to a single food plant. According to BugGuide: “Larvae are generalists of low herbacious plants” including many species commonly considered weeds.

  • Actually, this creature looks pretty cute.

  • Bonnie Schwartz
    September 17, 2017 1:47 pm

    I found all black fuzzy caterpillar, I thought it might be a woolly Bear with out the red stripe! Thanks to your web site I found the answer! Thank You 🙂 B. Schwartz

  • noticed a small patch on my wall. I live in the Monterey, CA area. I notice these on my wall. scared me because I didn’t know what they were. so I took tape- placed it over them and pressed hoping not to drop any. I then placed the tape in a plastic zip bag untill I could figure out what they were. they look just like what you have up on the site.

  • I found a similar Woolly Bear today. I am in Black Forest, El Paso county, Colorado, 80908 and live at 7500 feet elevation. Not sure how to post a photo

  • I just found one of these today! And was looking to identify it! I live in Cascade Colorado at about 8,000 elevatio! If i knew what it ate I would keep it to see!

    • They love kale… we have one here that is due to race in the famous wooly worm festival here in banner elk North Carolina this weekend… we used to live in CO too i never saw any out there but we lived in breck at 10000…

  • I recently found a completely white moth with only one black dot on each wing and an orange thorax. I tried looking it up online but nothing really looks exactly like it. This is my first time seeing it in Fountain, Colorado and I have lived here for more than ten years. Is this the same moth?


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