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BugGuide Gathering
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July 10-12, 2009
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Species Pyrrharctia isabella - Isabella Tiger Moth - Hodges#8129

Woolly Bear - Pyrrharctia isabella Pyrrharctia isabella Wooly Bear - Pyrrharctia isabella caterpillar - black and rusty orange in color - Pyrrharctia isabella Wolly Bear caterpillar (Isabella tiger moth) - Pyrrharctia isabella Isabella Tiger Moth - Pyrrharctia isabella Isabella Tiger Moth - Pyrrharctia isabella banded woolly bear caterpillar - Pyrrharctia isabella
Show images of: caterpillars · adults · both
Classification
Kingdom Animalia (Animals)
Phylum Arthropoda (Arthropods)
Class Insecta (Insects)
Order Lepidoptera (Butterflies and Moths)
No Taxon (Moths)
Superfamily Noctuoidea
Family Arctiidae (Tiger Moths)
Subfamily Arctiinae (Tiger Moths)
Tribe Arctiini
Genus Pyrrharctia
Species isabella (Isabella Tiger Moth - Hodges#8129)
Hodges Number
8129
Other Common Names
Banded Woolly Bear (caterpillar) (1)
Black-ended Bear (caterpillar) (2)
Synonyms and other taxonomic changes
Isia isabella
Size
Wingspan 45-65mm (2)
Larvae to 57mm (3)
Identification
Caterpillars are fuzzy and variably banded with black ends, rusty red in the center.

Range
Common throughout North America (3)
Season
Flies April to August (2)
Food
Larvae eats many plants and trees including grasses, asters, birches, clover, corn, elms, maples and sunflowers (2)(1)
Life Cycle
The first of two broods pupates in Summer. The second brood overwinters as a caterpillar and pupates in Spring. (2)
Remarks
The only species of Pyrrharctia. (1)

Folk wisdom holds that the relative lengths of the bands of the caterpillar foretell the severity of the coming winter (3). Actually, the variability of the bands depends on many factors. As larvae mature, the reddish bands lengthen (2). Wetter weather lengthens the black bands (1). So while not a reliable measure, it makes some sense that onset of an early and thus longer winter will force younger and less red caterpillars into hibernation.
Print References
Arnett provides a black and white adult photo, figure 27.291 (1).
Peterson's First Guide illustrates all life stages, page 99 (3).
Covell provides color illustrations of caterpillar and adult, plates 1 and 14 (2).
Internet References
Caterpillar account from University of Missouri Extension.
Natural history and tidbits from Iowa State University.
Caterpillar account at Caterpillars of Eastern Forests.