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Variously called wooly bears, wooly worms or wooly caterpillars, the larval form of the tiger moths are small, fuzzy insects of family Arctiidae. About 250 species inhabit North America, and many more live around the world. These moths are unusual not only for their fuzzy larval form but also because they make sounds to attract mates and repel predators.
The Reason for Fuzz
The fuzzy outer hair on wooly bear caterpillars makes the creatures less vulnerable to attack from predators. While experts seem to disagree whether the hairs on a wooly caterpillar act as irritants, they definitely provide a layer of protection between the caterpillars and danger. Some animals, such as skunks, roll the caterpillars around to remove the hair, some swallow them whole and others search for easier-to-eat prey. They lose this protection after metamorphosis and emerge as adult moths without their hairy covering.
Wooly Caterpillar Life Cycle
Wooly caterpillars start life as eggs laid by an adult tiger moth and attached to the leaves of plants during the warm summer months. Once they hatch, the tiny caterpillars begin to eat. These bugs aren’t known for being picky, and they will generally eat almost anything they find, including grass, weeds and garden plants. Unlike many caterpillars, wooly caterpillars don’t pupate over the winter but instead remain in caterpillar form and produce a cryoprotectant antifreeze chemical that keeps them from freezing to death.
Completing the Cycle
When spring arrives, the caterpillars begin feeding again until it’s time to pupate. At that point the wooly bears surround themselves with fuzzy cocoons into which they incorporate their caterpillar fuzz. They remain in this state while they transform from a caterpillar into tiger moths, the adult forms of these insects. When they’re ready, the moths emerge from their cocoons to eat, breed and lay the eggs of a new generation. Tiger moths typically have two generations each year.
About Tiger Moths
Each of the many different species of tiger moths has its own unique look. Some are white with colored bodies, while others have patterned wings covered with stripes, spots or other markings, which can make it hard to know if you’re looking at a tiger moth or not. They continue to feed throughout the summer by siphoning the juice from plants instead of chewing on leaves as they did when in the caterpillar stage.
- University of Illinois Extension: How to Care for Wooly Worms
- University of Virginia Mountain Lake Biological Station: Woolly Bear Caterpillar
- Penn State University Extension: Wooly Bear Caterpillars – Purported Peerless Prognosticators
- University of Wisconsin Milwaukee: Woolly Bear
- Texas A&M AgriLife Extension: Virgin Tiger Moth
- Hemera Technologies/PhotoObjects.net/Getty Images