Home / Erebidae Moth / Isabella Tiger Moth (Woolly Bear Moth / Pyrrharctia Isabella)

Isabella Tiger Moth (Woolly Bear Moth / Pyrrharctia Isabella)

Isabella Tiger Moth
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Isabella tiger moth of the Erebidae family is indigenous to the United States and parts of southern Canada. They are even called woolly worm, woolly bear, and banded woolly bear in their larval form.

Scientific Classification


  • Family: Erebidae
  • Genus: Pyrrharctia
  • Scientific Name: Pyrrharctia Isabella

Description and Identification

Caterpillar

Isabella Tiger Moth Caterpillar
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Woolly Bear Moth Caterpillar
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The larvae have a hairy, woolly, fuzzy appearance because of the dense and stiff hair covering their body, earning them the name woolly worm or woolly bear. They have brownish or reddish-brown hair at the center, while the anterior and posterior parts of their body remain covered in black setae.

It advisable for humans not to touch the larvae as their stingy hairs might lead to a skin infection. Yet, they are not venomous and do not result in any skin inflammation and irritation. Upon getting disturbed, they roll into a ball and crawl away quickly.

Pupa

Isabella Tiger Moth Pupa
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Isabella Tiger Moth Cocoon
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The pupa has a reddish-brown body remaining enclosed in a cocoon made of silk and larval hairs.

Adult Moth

Sexual Dimorphism: Present

The females appear larger than their male counterparts, while there is also a difference in coloration in their wings.

Color and Appearance

Forewings: When opened, they are tan or yellow with black spots and faint lines all over. When closed, it has the same yellow color and spotted appearance.

Hindwings: When opened, it appears a shade lighter than the forewings, with the color pattern varying in males and females. When closed, there is no significant change in the wing color and pattern.

Pyrrharctia isabella
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Woolly Bear Moth
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While males have a yellowish-orange hind wing with black spots on the outer margin, it appears pinkish in females.

Their abdomen’s color matches that of the wings, while they also have reddish-orange forelegs.

Average Wingspan: 3.7 – 5 cm (1.45 – 1.96 cm)

Flight Pattern: Erratic in a spiral and zigzag

Season: April – September

Eggs

Isabella Tiger Moth Eggs
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The tiny eggs have a yellowish-green coloration that hatches in fall.

Quick Facts

Other NamesWoolly worm, woolly bear, banded woolly bear (names of the larvae)
DistributionThroughout the United States except for Hawaii and Alaska
HabitatMostly in and around areas where their host plants grow
PredatorsParasitic wasps, flies, birds, mantids
Lifespan of Adults1 – 2 week
Host plantsAster, clover, birch, maple, elm, sunflower, corn
Adult dietNectar of their host plants

Did You Know

  • English botanist Sir James Edward Smith named this moth species for the first time in 1797.
  • As per the U.S. and Canadian folklore, the amount of black or brown hair on the larvae’s body determines the severity of winters. Longer and darker hairs are equivalent to harsher and colder winters.
  • Because of the woolly bear larvae’s remarkable association with winter, the woolly bear festival is celebrated in several locations like Ohio, Kentucky, and North Carolina during fall.
Isabella Tiger Moth Image
Isabella Tiger Moth Photo
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Woolly Bear Caterpillar Moth
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