Isabella tiger moth

(Pyrrharctia isabella)

Isabella tiger moth
Photo by Bill Reynolds
  Hodges #

8129

 
 
Conservation Status
  IUCN Red List

not listed

 
  NatureServe

N5 - Secure

 
  Minnesota

not listed

 
           
 
Description
 
 

In its larval (caterpillar) stage, Isabella tiger moth may be the most widely recognized moth in North America. Folklore says that the size of the orange band predicts the severity of the coming winter, with wider bands forecasting a milder winter. This means of forecasting is probably as accurate as the Farmer’s Almanac, though perhaps not as accurate as the National Weather Service.

The adult is less conspicuous but equally distinctive. The adult moth has a wingspan of 1¼ to 2 and a total length of 15 16 to 15 16. The thorax is densely covered with long brown or yellowish-brown hairs. The abdomen is orange with an upper (dorsal) row of black spots.

The forewings are pointed and are uniformly light to medium orangish-brown. On some individuals there is a fringe of reddish-orange hairs on the outer margin. The veins are marked with faint brown spots. There is a series of black spots on the subterminal line and often one or more spots on the antemedial, median, and postmedial lines. The discal spot has a group of 3 to 5 black spots. The hindwing of males are pale orange with a black discal spot and black spots near the margin. The hindwing of females is pale rose but otherwise similar.

The caterpillar is up to 2 long and is densely covered with stiff bristles (setae) from front to back. There are also a few longer, softer hairs extending from the front and back of the body. The setae are in clusters of several and are mostly uniform in length. On most caterpillars the setae are black on the head, thorax, and first few and last few abdominal segments; and orange on the middle abdominal segments. As the caterpillar ages and grows, it sheds its skin and setae (molts) several times. At each successive stage between molts (instar) it becomes more orange. On some individuals all of the setae are blond, brown, rust, or tan. There is a small breathing hole (spiracle) on both sides of each thoracic segment and all but the last abdominal segment. On pale individuals the spiracles are tan or white.

 
     
 

Size

 
 

Total length: 15 16 to 15 16

Wingspan: 1¾ to 2½

 
     
 

Similar Species

 
     
     
 
Habitat
 
 

Deciduous woodlands, prairies

 
     
 
Biology
 
 

Season

 
 

One brood. Early June to late July.

 
     
 

Behavior

 
 

Caterpillars are especially mobile in the fall. When disturbed, they curl up into a ball.

Adults are nocturnal. They are attracted to lights.

 
     
 

Life Cycle

 
 

Eggs hatch after about two weeks. Caterpillars overwinter under leaf litter or other debris, where they freeze solid. In the spring they become active and resume feeding. After a few days then spin a cocoon to pupate. Adults emerge in about a month.

 
     
 

Larva Hosts

 
 

Deciduous trees and a wide range of low growing herbaceous and woody plants.

 
     
 

Adult Food

 
 

Adults do not feed.

 
     
 
Distribution
 
 

Distribution Map

 

Sources

21, 24, 27, 29, 30, 71, 75, 82.

 
  8/26/2022      
         
 

Occurrence

 
 

Widespread and common

 
         
 
Taxonomy
 
 

Order

Lepidoptera (butterflies and moths)  
 

Superfamily

Noctuoidea (owlet moths and allies)  
 

Family

Erebidae (underwing, tiger, tussock, and allied moths)  
 

Subfamily

Arctiinae (tiger moths and allies)  
 

Tribe

Arctiini (tiger moths)  
  Subtribe Spilosomina  
 

Genus

Pyrrharctia  
       
 

Until recently, tiger moths and lichen moths were treated as a separate family Arctiidae. A recently published monograph (Lafontaine and Schmidt, 2010) contended that the Arctiidae “were more closely related to groups within the Noctuidae than to non-noctuid families.” The Arctiidae were transferred intact to the family Erebidae as a subfamily (Arctiinae). The former subfamilies are now tribes and the former tribes are now subtribes.

 
       
 

Synonyms

 
 

Isia isabella

 
       
 

Common Names

 
 

banded woollybear

black-ended bear

Isabella tiger moth

woolly bear

 

 

 

 

 

 

 

 

Glossary

Instar

The developmental stage of arthropods between each molt; in insects, the developmental stage of the larvae or nymph.

 

Seta

A usually rigid bristle- or hair-like structure on butterflies and moths used to sense touch. Plural: setae.

 

Spiracle

A small opening on the surface of an insect through which the insect breathes.

 

 

 

 

 

 
 
Visitor Photos
 
           
 

Share your photo of this insect.

 
  This button not working for you?
Simply email us at info@MinnesotaSeasons.com.
Attach one or more photos and, if you like, a caption.
 
 

Luciearl

 
 

Banded woolly bear on Joe pye-weed

 
    Isabella tiger moth      
 

Alfredo Colon

 
    Isabella tiger moth   Isabella tiger moth  
           
    Isabella tiger moth   Isabella tiger moth  
 

Greg Watson

 
    Isabella tiger moth      
 

Petra

 
    Isabella tiger moth      
 

Margot Avey

 
    Isabella tiger moth      
 

krader0225

 
    Isabella tiger moth      
 

Bill Reynolds

 
    Isabella tiger moth   Isabella tiger moth  
           
    Isabella tiger moth      
           
 
MinnesotaSeasons.com Photos
 
 

 

 
           

 

Camera

     
 
Slideshows
 
Isabella Tiger Moth
DianesDigitals
  Isabella Tiger Moth  
 
About

Copyright DianesDigitals

 
Woolly Bear Caterpillar
Andree Reno Sanborn
  Woolly Bear Caterpillar  
 
About

Pyrrharctia isabella (larval form)
bugguide.net/node/view/493/bgimage

larva:

adult is the Giant Leopard Moth:
bugguide.net/node/view/493/bgimage

 
Pyrrharctia isabella (Isabella Tiger Moth)
Allen Chartier
  Pyrrharctia isabella (Isabella Tiger Moth)  

 

slideshow

       
 
Visitor Videos
 
       
 

Share your video of this insect.

 
  This button not working for you?
Simply email us at info@MinnesotaSeasons.com.
Attach a video, a YouTube link, or a cloud storage link.
 
 

@annahalo

 
  Pyrrharctia Isabella. Isabella Tiger Moth Caterpillar!
Sep 25, 2023
 
   
 
About

Pyrrharctia Isabella. Isabella Tiger Moth Caterpillar! #shorts @annahalo Thank you to all my Fans and Friends!

   
       
 
Other Videos
 
  Isabella Tiger Moth (Erebidae: Pyrrharctia isabella) Caterpillar
Carl Barrentine
 
   
 
About

Uploaded on Oct 6, 2010

Photographed on a blustery afternoon near Fisher, Minnesota (04 October 2010).

 
  Run, Woolly, Run!
SquirrelOnRoad
 
   
 
About

Uploaded on Oct 14, 2008

A Woolly Bear (the caterpillar stage of the Isabella tiger moth, Pyrrharctia isabella) showed up in the yard, so I recorded it running away. Maybe it thought I was a predator. Boy, I've never seen one move so fast!

 
  Banded Woolly Bear Caterpillar (Pyrrharctia Isabella)
juniortore1
 
   
 
About

Uploaded on Jan 23, 2012

Just some quick footage of a banded woolly bear caterpillar I rescued from the pool. They turn into a isabella tiger moth.

 
  Wooly bear caterpillar (Pyrrharctia isabella)
erminehustler
 
   
 
About

Published on Oct 4, 2012

Larval form of Isabella's tiger moth. Amherst, VA. Slow speed.

 

 

Camcorder

 
 
Visitor Sightings
 
           
 

Report a sighting of this insect.

 
  This button not working for you?
Simply email us at info@MinnesotaSeasons.com.
Be sure to include a location.
 
  @annahalo
9/25/2023

Location: Sault Ste. Marie, Ontario Canada

 
  Greg Watson
8/10/2022

Location: La Crescent, MN

Isabella tiger moth

 
  Alfredo Colon
8/8/2022

Location: Albany, NY

Isabella tiger moth

 
  Petra
4/1/2020

Location: St. Paul, MN

they are unusual. :)

Isabella tiger moth

 
  Alfredo Colon
10/6/2019

Location: Woodbury, Minnesota

Isabella tiger moth

 
  Margot Avey
3/23/2019

Location: St. Louis Park, MN

Isabella tiger moth

 
  krader0225
10/21/2018

Location: Roanoke VA

Isabella tiger moth

 
  Peggy Haskin
12/23/2017

Hello:  I found a woolly bear caterpillar in my house today.  I thought he was dead, but when I touched him he curled up.  I'd like to save the little critter, but if I put him outside (it's 20 degrees here today), I'm afraid he'll immediately freeze.  I have a small tree planted in a large pot in my house, so I put him on top of the soil.  He's crawling around.  I looked online and saw directions for "overwintering" him, but it said I should collect leaves from outside to feed him. Well, as you know, there are no leaves outside.  Can you give me some advice on what to do with him?  Thanks so much.

 
  John Valo
12/23/2017

Maybe put in in a refrigerator with a potted plant (for it to hang from) in the hope that it will create a cocoon and pupate. The cold may be the trigger it needs.

 
  Bill Reynolds
12/17/2015

Location: Pennington Co. MN

… this fall we had tons of Woolly Bear caterpillars crawling about the yard.

Isabella tiger moth

 
  Bill Reynolds
9/22/2014

Location: Pennington Co. MN

Woolly Worm, the caterpillar stage of the Isabelle Tiger moth.

Isabella tiger moth

 
           
 
MinnesotaSeasons.com Sightings
 
   

 

 

Binoculars


Created 9/23/2014

Last Updated:

About Us | Privacy Policy | Contact Us | © MinnesotaSeasons.com. All rights reserved.