You may find little puffballs resting on plants – but when they move, you know they’re white woolly worms! These voracious eaters are generally identified as the caterpillar phase of the Yellow Woolly Bear moth; also known as the Virginia tiger moth. Technically, they’re called Spilosoma virginica.
Although they may have first been identified in the state of Virginia, white woolly worms can be found in many parts of the U.S. As a tiger moth species, they’re members of the Arctiidae family. Perhaps the best-recognized larva in this group is the banded woolly bear, which as an adult is known as the Isabella tiger moth.
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The Virginia tiger moth caterpillar is usually yellow. However, during an early phase or sometimes as an aberration, the woolly bear worms are white. If they’re very young, they’ll eventually turn yellow and then orange before beginning the pupation stage.
Adult Virginia tiger moths are quite beautiful. Tiger moths first received their name from the displays of striking colors and patterns that often rival butterflies. Virginia tiger moths sport a crown of white fuzz and snowy wings with random, small black spots. Their bodies may also feature repeating geometric styled dots along the sides. Look at them from underneath and you may see shades of orange around the head area.
As white woolly worms, they behave like other caterpillar species. In other words, they’ll eat everything in sight before weaving a cocoon. Newly hatched, they’ll group together while they feed. As they develop, though, they’ll become more solitary, which makes them difficult to spot.
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This moth species may be present through three life cycles annually. Some will overwinter in the caterpillar stage, tucking away under leaves and logs. In the spring, they continue growing before weaving a cocoon in preparation for adulthood. As adults, they tend to rest with wings raised to a point, referred to as “tenting.” Most moths, on the other hand, will spread their wings.
Woolly worms eat weeds, which makes them less of a threat to plant lovers in some areas. Those that do appear on other vegetation are called “general feeders.” White woolly bear worms may also feed on vegetables and clover along with a host of aquatic plants. Rarely, you may spot them munching on the leaves of fruit trees. Even when they overpopulate, they do little damage.
White woolly worms are most common, in the fall. In fact, they’re the only “hairy” caterpillars active in autumn. If you try to pick one up, it will curl into a ball. Handle it at all, and its bristly white hairs will begin to fall off.
When the white woolly worms emerge as adult moths, they fly at night, which is common among many species.