Other Common Names
Yellow Woolybear, Yellow Bear (caterpillar) (1)
Synonyms and other taxonomic changes
Spilosoma virginica (Fabricius)
Orig. Comb: Bombyx virginica Fabricius, 1798
Caterpillars exceedingly 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. (1)
Widespread throughout most of North America, but more common in the east - Map
among the most common caterpillars on plantings about yards and gardens, also in bottomlands, woodlands, and forests (1)
Mature caterpillars May through November (1)
Caterpillars feed on "many low-growing plants, and woody shrubs and trees"(1)
; "uses common milkweed frequently in southwest Michigan. Have found their eggs on common milkweed and raised them to adulthood on it." (Ilse Gebhard, pers. comm. 2016, to MAQ)
Click on any image below to view the Life Cycle:
1. Eggs. 2. Caterpillar. 3. Pupa. 4. Pupa in its cocoon. 5. Adult
*Note: This species is very often confused with Spilosoma congrua and Hyphantria cunea where ranges overlap. When a view of the abdomen is not possible, one of the key clues as to which species, lies with the appearance of the legs: in particular, the tibiae and tarsi of the forelegs. The key to using this characteristic to separate these three species is as follows:
S.congrua; tibiae and tarsi will be solid white laterally, bordered by solid black medially along the interior of the tibiae/tarsi with a clear demarcation and no banding on tarsi.
S.virginica; tibiae and tarsi will be strongly white with complete or partial black banding dorsally along the tarsi.
H. cunea; tibiae and tarsi vary – in immaculate specimens the tibiae/tarsi is often completely white/pale, while in heavily marked specimens, the tibiae/tarsi are completely black. In other lighter marked specimens, tarsi may appear banded and most similar to S.virginica, but will only appear so laterally with solid black/dark medially. When dealing with this variation, it’s typically described as H.cunea having dark tibiae/tarsi, the tarsi banded with white, verses S.virginica having mostly white tibiae/tarsi, the tarsi banded with black.
Where an egg mass is present, another clue is available. The egg masses of S.virginica are typically yellow, of S.congrua typically white, and those of H.cunea, a very pale green.
Salt Marsh Caterpillar Estigmene acrea
. Caterpillars also have long soft hairs - longest hairs are concentrated at the ends of the larva, especially the rear.
Adult: S. virginica has yellow markings on the abdomen, while S. congrua's abdomen is pure white. [comment by Paul Dennehy]
- images of all life stages